Attention:

Certain features of Sigma-Aldrich.com will be down for maintenance the evening of Friday August 18th starting at 8:00 pm CDT until Saturday August 19th at 12:01 pm CDT.   Please note that you still have telephone and email access to our local offices. We apologize for any inconvenience.

PKC

Protein kinase C (PKC) is an AGC kinase that phosphorylates serine and threonine residues in many target proteins. It was first identified in 1977 in bovine cerebellum by Nishizuka and co-workers as a protein kinase that phosphorylated histone and protamine. Since then, its involvement in many biological processes has been demonstrated, including development, memory, differentiation, proliferation and carcinogenesis. Once thought to be a single protein, PKC is now known to comprise a large family of enzymes that differ in structure, cofactor requirements and function. Ten isoforms of PKC have been identified, varying in tissue expression and cellular compartmentalization, allowing for specific interactions with substrates.

The PKC family has been divided into three groups, differing in the enzymes' cofactor requirements; conventional (c)PKC isoforms (comprising α, βI , βII and γ), that require calcium and diacylglycerol (DAG) for activation; novel (n)PKC isoforms (comprising δ, ε, η {also known as PKC-L}, and θ that require DAG; and atypical (a)PKC isoforms, namely ζ, and ι (also known as λ, the mouse homolog of human PKCι) that require neither calcium nor DAG. Protein kinase D (PKD) is a distinct kinase family that was originally classified as a PKC subgroup (PKCμ, PKCv). The PKC-related kinases (PRK/PKN) contain kinase domains homologous to PKC's. These are not closely related to the PKC family due to very different regulatory domains; however, they can be considered to be part of the PKC superfamily.

All PKCs possess a phospholipid-binding domain for membrane interaction. The general structure of a PKC molecule consists of a catalytic and a regulatory domain, composed of a number of conserved regions, interspersed with regions of lower homology, the variable domains.

Activation of cPKCs involves translocation from the cytosol to the cell membrane by engaging the membrane-targeting modules. In the case of cPKCs, an increase in intracellular calcium first promotes the binding of the C2 domain to anionic lipids. The C1 domain binds DAG (or phorbol esters, functional DAG-analogs) and phosphatidylserine (PS), recruiting the conventional and novel PKCs to the membrane, where they can phosphorylate substrates. Specific anchoring proteins (immobilized at particular intracellular sites) localize the kinase to its site of action. These proteins include 'receptors for activated C-kinase' (RACKS), 'receptors for inactive C-kinase' (RICKS), 'A-kinase anchoring proteins' (AKAPS), and 'substrates that interact with C-kinase' (STICKS). In addition, nuclear localization signals (NLS) or nuclear export signals (NES) can send PKC into or out of the nucleus.

Some, if not all, PKC isoforms can be proteolytically cleaved at the hinge between the regulatory and catalytic domains by proteases such as the calcium-activated calpain, generating a free, cofactor-independent, catalytic subunit known as protein kinase M (PKM). This 'calpain product' should not be considered an 'unregulated' enzyme since its generation is, in fact, regulated by proteolysis. Cleavage is a physiologically relevant alternate activation mechanism for isozymes such as PKCδ, occurring in processes like apoptosis, where caspases appear to have important roles.

All PKCs, except the δ isoform, exhibit so-called PEST sequences, hydrophilic polypeptide segments enriched in proline (P), glutamic acid (E), serine (S) and threonine (T), which target proteins for degradation by the proteasome. An additional level of complexity is apparent following the observation that dephosphorylation of activated PKCs apparently predisposes them to ubiquitination and degradation. The downregulation of PKC is therefore also regulated by specific phosphatases and ubiquitin ligases.

PKC isoforms are processed by three ordered priming phosphorylations. The first phosphorylation is catalyzed by phosphoinositide-dependent kinase (PDK-1) and occurs at the activation loop (T500 in PKCβII). This phosphorylation triggers two phosphorylations at the carboxy-terminus (T641 and S660 in βII). Each phosphorylation event induces conformational changes in the PKC molecule that result in altered thermal stability, resistance to phosphatases and catalytic competency.

The first complete crystal structure of PKC was obtained for the novel isoform θ. Previous structural information was obtained from crystals of the regulatory domains, and by modeling the catalytic domain with protein kinase A.

 

The Table below contains accepted modulators and additional information. For a list of additional products, see the "Similar Products" section below.

 

Family Members/Isoforms α
(P1782)
βI
(P1787)
βII
(P3287)
γ
(P9542)
δ
(P8538)
Other Names Conventional Conventional Conventional Conventional Novel
Molecular Weight
(kDa)
76.8 kDa (h) 76.7 kDa (h) 76.8 kDa (h) 78.4 kDa (h) 77.7 kDa (h)
Structural Data 672 aa (h) 671 aa (h) 673aa (h) 697 aa (h) 676 aa (h)
Species Ubiquitous
e.g. human (h)
Ubiquitous
e.g. human (h)
Ubiquitous
e.g. human (h)
Ubiquitous
including human
Ubiquitous
including human
Domain
Organization
N-terminal pseudosubstrate domain
C1A domain
C1B domain
C2 domain
Catalytic domain
C-terminal domain
N-terminal pseudosubstrate domain
C1A domain
C1B domain
C2 domain
Catalytic domain
C-terminal domain
N-terminal pseudosubstrate domain
C1A domain
C1B domain
C2 domain
Catalytic domain
C-terminal domain
N-terminal pseudosubstrate domain
C1A domain
C1B domain
C2 domain
Catalytic domain
C-terminal domain
N-terminal C2 domain
Pseudosubstrate domain
C1A domain
C1B domain
Catalytic domain
C-terminal domain
Phosphorylation
Sitesa
Thr497
Thr638
Ser657 (r,m,h,rb)
Thr500
Thr642
Ser661 (r,m,h,rb)
Thr500
Thr641
Ser660 (r,m,h)
Thr514
Thr655
Thr674 (r,m)
Thr505
Ser643
Ser662 (r,m,h)
Thr565
Ser709
Ser728 (rb)
Tissue
Distribution
Many; e.g. CNS, heart, kidney, liver, lung Many; e.g. CNS, heart, kidney, liver, lung Many; e.g. CNS, heart, kidney, liver, lung CNS Many; e.g. CNS, heart, kidney, liver, lung
Subcellular
Localization
Cytosol
Membrane
Cytosol
Membrane
Cytosol
Membrane
Cytosol
Membrane
Cytosol
Membrane
Mitochondria
Binding
Partners/
All isoforms: many, e.g. RACKs, STICKs, AKAPs.  See Referenceb in Footnotes.
Associated
Proteinsb
e.g. 14-3-3 e.g. 14-3-3
Spectrin
e.g. 14-3-3 e.g. 14-3-3 e.g. 14-3-3
Connexin43
Upstream
Activators
Conventional and novel isoforms: G-protein coupled receptors, tyrosine kinase receptors, non-receptor tyrosine kinase receptors, and other agonists of phospholipid hydrolysis, atypical isoforms: binding proteins, e.g. p62/zip, par6
Downstream
Activationc
MBP (M1891)
Histones (eg. IIIS)
EGFr
MARCKS
Protamine (P4505)
AKAP79
GAP43
Pleckstrin
Adducin
Vinculin
MBP (M1891)
Histone H3 (H4380)
EGFr
MARCKS
Protamine (P4505)
AKAP79
GAP43
Pleckstrin
MBP (M1891)
Histone H3 (H4380)
EGFr
MARCKS
Protamine (P4505)
AKAP79
GAP43
Pleckstrin
MBP (M1891)
Histone H3 (H4380)
EGFr
MARCKS
Protamine (P4505)
GAP43
Pleckstrin
Connexin43
MBP (M1891)
Histones (eg. IIIS)
EGFr
Protamine (P4505)
MARCKS
GAP43
Pleckstrin
STAT1
STAT3
Adducin
Substrates α Pseudosubstrate peptide
MBP peptide (P2186)
Syntide 2
EGFr peptide (L9905)
PKC substrate
MARCKS peptide
α Pseudosubstrate peptide
MBP peptide (P2186)
Syntide 2
EGFr peptide (L9905)
PKC substrate
MARCKS peptide
α Pseudosubstrate peptide
MBP peptide (P2186)
Syntide 2
EGFr peptide (L9905)
PKC substrate
MARCKS peptide
α Pseudosubstrate peptide
MBP peptide (P2186)
Syntide 2
EGFr peptide (L9905)
PKC substrate
MARCKS peptide
α Pseudosubstrate peptide
ε Pseudosubstrate peptide
MBP peptide (P2186)
EGFr peptide (L9905)
PKC substrate
eEF-1α
MARCKS peptide
Activatorsd Ca2+
DAG (O6754)
PDA (P9143)
PDBu (P1269)
PDD (P9018)
PMA (P8139)
PS (P5660, P6641, P7769)
Ca2+
DAG (O6754)
PDA (P9143)
PDBu (P1269)
PDD (P9018)
PMA (P8139)
PS (P5660, P6641, P7769)
Ca2+
DAG (O6754)
PDA (P9143)
PDBu (P1269)
PDD (P9018)
PMA (P8139)
PS (P5660, P6641, P7769)
Ca2+
DAG (O6754)
PDA (P9143)
PDBu (P1269)
PDD (P9018)
PMA (P8139)
PS (P5660, P6641, P7769)
DAG (O6754)
PDA (P9143)
PDBu (P1269)
PDD (P9018)
PMA (P8139)
PS (P5660, P6641, P7769)
Inhibitorse Calphostin C (C6303)
Ro 31-8220 (R136)
GF109203X (G2911)
Gö 6976 (G1171)
K252a (K1639, K2015)
Ro 31-7549
Gö 6983 (G1918)
Chelerythrine chloride (C2932)
(–)-Balanol
UCN-01 (U6508)
CGP41251
CGP54345
CGP53506
Aprinocarsen
CGP53506
Calphostin C (C6303)
Ro 31-8220 (R136)
GF109203X (G2911)
Gö 6976 (G1171)
K252a (K1639, K2015)
Ro 31-7549
Gö 6983 (G1918)
Chelerythrine chloride (C2932)
(–)-Balanol
UCN-01 (U6508)
CGP41251
LY-333531 (SML0693)
LY379196
LY317615 (SML0762)
Aprinocarsen
Calphostin C (C6303)
Ro 31-8220 (R136)
GF109203X (G2911)
Gö 6976 (G1171)
K252a (K1639, K2015)
Ro 31-7549
Gö 6983 (G1918)
(–)-Balanol
UCN-01 (U6508)
CGP41251
LY-333531 (SML0693)
LY379196
LY317615 (SML0762)
Calphostin C (C6303)
Ro 31-8220 (R136)
GF109203X (G2911)
Gö 6976 (G1171)
K252a (K1639, K2015)
Ro 31-7549
Gö 6983 (G1918)
Chelerythrine chloride (C2932)
(–)-Balanol
UCN-01 (U6508)
CGP41251
Calphostin C (C6303)
Gö 6983 (G1918)
Chelerythrine chloride (C2932)
LY-333351 (SML0693)
(–)-Balanol
Rottlerin (R5648)
Selective
Activators
Not Known Not Known Not Known Not Known Not Known
Physiological
Function
Cell motility
Migration
Apoptosis
Cell growth
Immune function
B-cell survival
Cell growth
Immune function
B-cell survival
Antiapoptotic
Nociceptive response
Spatial learning
Neuroplasticity
Proapoptotic
Growth
Differentiation
Platelet granular secretion
Disease
Relevance
Cardiac hypertrophy
Heart failure
Prostate cancer
Breast cancer
Chemo therapeutic resistance
Cardiac hypertrophy
Heart failure
Gastric cancer
Cardiac hypertrophy
Heart failure
Leukemia
Colon cancer
Spinocerebellar ataxia
Lymphoma
Cardiac hypertrophy
Cardiac ischemic injury
Prostate cancer
Leukemia

 

 

Family Members/Isoforms ε η/L θ ζ ι/λ
Other Names Novel Novel Novel Atypical Atypical
Molecular Weight
(kDa)
83.5 kDa (h) 77.9 kDa (h) 81.9 kDa (h) 67.7 kDa (h) 67.3 kDa (h)
Structural Data 737 aa (h) 680 aa (h) 706 aa (h) 592 aa (h) 587 aa (h)
Species Ubiquitous
including human
Ubiquitous
e.g. human
Ubiquitous
e.g. human
Ubiquitous
e.g. human
Ubiquitous
e.g. human
Domain
Organization
N-terminal C2 domain
Pseudosubstrate domain
C1A domain
C1B domain
Catalytic domain
C-terminal domain
N-terminal C2 domain
Pseudosubstrate domain
C1A domain
C1B domain
Catalytic domain
C-terminal domain
N-terminal C2 domain
Pseudosubstrate domain
C1A domain
C1B domain
Catalytic domain
C-terminal domain
N-terminal PB1 domain
Pseudosubstrate domain
Atypical C1 domain
Catalytic domain
C-terminal domain
N-terminal domain
PB1 domain
Pseudosubstrate domain
Atypical C1 domain
Catalytic domain
C-terminal domain
Phosphorylation
Sitesa
Thr566
Thr710
Ser729 (h,r)
Thr512
Thr655
Ser674 (h)
Thr513
Thr656
Ser675 (r,m)
Thr538
Ser676
Ser695 (m,h)
Thr410
Thr560 (r,m,h)
Thr412
Thr564 (h)
Tissue
Distribution
Many; e.g. CNS, heart, kidney, liver, lung Many; e.g. CNS, heart, lung, spleen Many; e.g. CNS, heart, liver, airway smooth muscle, lung Many; e.g. CNS, heart, kidney, liver, lung Many; e.g. CNS, heart, airway smooth muscle, liver, lung
Subcellular
Localization
Cytosol
Membrane
Golgi
Cytosol
Membrane
Cytosol
Membrane
Cytosol
Membrane
Cytosol
Membrane
Binding
Partners/
All isoforms: many, e.g. RACKs, STICKs, AKAPs.  See Referenceb in Footnotes.
Associated
Proteinsb
e.g. integrins
Connexin43
e.g. cdk2 e.g. IKKβ e.g. p62/ZIP
Par6
mek5
e.g. p62
ZIP5
mek5
LIP
Par6
Upstream
Activators
Conventional and novel isoforms: G-protein coupled receptors, tyrosine kinase receptors, non-receptor tyrosine kinase receptors, and other agonists of phospholipid hydrolysis, atypical isoforms: binding proteins, e.g. p62/zip, par6
Downstream
Activationc
MBP (M1891)
Histones
EGFr
Protamine (P4505)
MARCKS
GAP43
Pleckstrin
MBP (M1891)
Histones
EGFr
Protamine (P4505)
MARCKS
GAP43
Pleckstrin
Integrin βII
MBP (M1891)
Histones
EGFr
Protamine (P4505)
MARCKS
GAP43
Pleckstrin
MBP (M1891)
Histones
EGFr
Protamine (P4505)
Pleckstrin
MBP (M1891)
Histones
EGFr
Protamine (P4505)
Pleckstrin
MARCKS
Substrates α Pseudosubstrate peptide
ε Pseudosubstrate peptide (P4459)
ε Substrate
MBP peptide (P2186)
EGFr peptide (L9905)
PKC substrate
MARCKS peptide
η Substrate
α Pseudosubstrate peptide
ε Pseudosubstrate peptide (P4459)
MBP peptide (P2186)
EGFr peptide (L9905)
PKC substrate
MARCKS peptide
θ Substrate
α Pseudosubstrate peptide
MBP peptide (P2186)
EGFr peptide (L9905)
PKC substrate
MARCKS peptide
ε Substrate
ε Pseudosubstrate peptide (P4459)
α Pseudosubstrate peptide
MBP peptide (P2186)
EGFr peptide (L9905)
PKC substrate
ε Pseudosubstrate peptide (P4459)
α Pseudosubstrate peptide
MBP peptide (P2186, M8184)
EGFr peptide (L9905)
PKC substrate
MARCKS peptide
Activatorsd DAG (O6754)
PDA (P9143)
PDBu (P1269)
PDD (P9018)
PMA (P8139)
PS (P5660, P6641, P7769)
DAG (O6754)
PDA (P9143)
PDBu (P1269)
PDD (P9018)
PMA (P8139)
PS (P5660, P6641, P7769)
DAG (O6754)
PDA (P9143)
PDBu (P1269)
PDD (P9018)
PMA (P8139)
PS (P5660, P6641, P7769)
PS (P5660, P6641, P7769)
p62/ZIP
Par6
PS (P5660, P6641, P7769)
p62/ZIP
Par6
Inhibitorse Calphostin C (C6303)
GF109203X (G2911)
Gö 6983 (G1918)
LY-333531 (SML0693)
(–)-Balanol
Calphostin C (C6303)
GF109203X (G2911)
Gö 6983 (G1918)
LY-333351 (SML0693)
(–)-Balanol
η pseudosubstrate peptide
NPC 15437 (N161)
Calphostin C (C6303)
GF109203X (G2911)
Gö 6983 (G1918)
LY-333531 (SML0693)
(–)-Balanol
θ pseudosubstrate peptide
Gö 6983 (G1918)
ζ pseudosubstrate peptide (P1614)
Gö 6983 (G1918)
Selective
Activators
Not Known Not Known Not Known Not Known Not Known
Physiological
Function
Cell migration
Antiapoptotic
Nociceptive response
Macrophage activation
Antiapoptotic
Cell cycle
Differentiation
B-cell development
Immune function (T-cell signaling)
Cytoskeletal assembly
Antiapoptotic
Immune function (B-cell signaling)
Cell polarity
Antiapoptotic
Cell polarity
Antiapoptotic
Insulin sensitivity
Disease
Relevance
Cardiomyopathy
Ischemic preconditioning
Alzheimer’s disease
Lung cancer
Colorectal cancer
Skin cancer
Diabetes
Glioblastoma
Lung cancer
Renal cancer
Skin cancer
Breast cancer
Gastrointestinal cancer
Breast cancer
Leukemia
Colon cancer
Pancreatic cancer
Renal cancer
Leukemia
Colon cancer
Leukemia
Diabetes

 

Footnotes

a) Processing sites listed.

b) For detailed list of binding partners, see Reference: Poole, A.W., et al. “PKC-interacting proteins: from function to pharmacology.” Trends Pharmacol Sci, 25, 528-535 (2004).

c) PKCα pseudosubstrate site sequence RFARKGALRQKNVHEVKDH. PKCε pseudosubstrate site sequence PRKRQGAVRRRVHQVNGH (underlined are mutable sites for phosphorylateable residues). Substrates not determined on all isoforms.

d) Specific lipid activator of aPKCs unknown. Less is known about activators/substrates/inhibitors of aPKCs than nPKCs than cPKCs. Activators not determined on all isoforms.

e) GF 109203X (Gö 6850 aka BIM 1) displays potency rank order of α>βI>ε>δ>ζ. Bisindolylmaleimides (Ro compounds, BIM 1, Gö 6976) inhibit all PKCs in potency rank order of cPKCs>nPKCs>aPKCs (generally); Calphostin C inhibits DAG site in regulatory domain; BIM 1 and Ro compounds act at ATP site; Chelerythrine chloride inhibits substrate site in catalytic domain.

 

Abbreviations

AKAP: A-Kinase Anchoring Protein
Aprinocarsen: ISIS 3521
Cdk2: Cyclin dependent kinase 2
CGP41251: (PKC412): Staurosporine derivative
CGP54345: ATP analog
CGP53506: N-(3-Nitrophenyl)-4-(3-pyridyl)-2-pyrimidinamine
eEF-1α: Eukaryotic elongation factor-1α peptide, residues 422-443.
Gö 6976: 5,6,7,13-Tetrahydro-13-methyl-5-oxo-12H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-12-propanenitrile
Gö 6983: 2-[1-(3-Dimethylaminopropyl)-5-methoxyindol-3-yl]-3-(1H-indol-3-yl)maleimide
GF 109203X: 3-[1-[3-(Dimethylamino)propyl]-1H-indol-3-yl]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione (Gö6850)
LIP: PKC 1 interacting protein to PKC λ interacting protein
LY-333531: 9-[(Dimethylamino)methyl]-6,7,10,11-tetrahydro-(9S)-NH,18H-5,21:12,15-dimetheno-dibenzo[e,k]pyrrolo[3,4-h][1,4,13]oxadiazacyclohexadecine-18,20(19H)dione
K252a: Staurosporine-related alkaloid
MARCKS peptide: Myristoylated alanine-rich C-kinase substrate, Ac-phe-lys-lys-ser-phe-lys-leu-NH2
MBP: Myelin basic protein
NPC 15437: S-2,6-Diamino-N-[[1'-(1''oxotridecyl)-2'-piperidinyl]methyl]hexanamide dihydrochloride
PB1: Phox and Bem1p binding domain
PDA: Phorbol 12, 13-diacetate
PDBu: Phorbol 12, 13-dibutyrate
PDD: Phorbol 12, 13-didecanoate
Pleckstrin: Platelet and leukocyte C-kinase substrate protein
PMA: Phorbol 12-myristate 13-acetate
PS: Phosphatidylserine
RACK: Receptors for Activated C-Kinase
Ro 31-7549: 2-[1-3(Aminopropyl)indol-3-yl]-3(1-methyl-1H-indol-3-yl)maleimide
Ro 31-8220: 2-{1-[3-(Amidinothio)propyl]-1H-indol-3-yl}-3-(1-methylindol-3-yl)-maleimide)
STAT: Signal Transducers and Activators of Transcription
STICK: Substrates That Interact with C-Kinase
Syntide 2: H-pro-leu-ala-arg-thr-leu-ser-val-ala-gly-leu-pro-gly-lys-lys-OH
TPA: Tetra phorbol acetate
UCN-01: 7-Hydroxy-staurosporine
ZIP: PKC Zeta interacting protein

r: Rat
h: Human
m: Mouse
rb: Rabbit

 

Similar Products


     

References