Antibodies to MAGI-1, MAGI-2, MAGI-3/SLIPR

The MAGUK (Membrane Associated Guanylate kinase) family of proteins, whose prototypic member is PS95, is characterized by the presence of multi-PDZ and SH3 domains, and a single region of homology to Saccharomyces cerevisiae guanylate kinase (Guk) domain.1

All MAGUK studied to date localize to regions of cell-cell contact, such as tight junctions in epithelial cells and synaptic junctions in neurons, and are believed to be involved in the assembly of multiprotein complexes via their protein-protein interaction domains.2 Using different screening systems, three novel closely related MAGUK protein were isolated: MAGI-1/BAP1, MAGI-2/rSCAM and MAGI-3/SLIPR. Similar to other MAGUK members, these three proteins have the characteristic multi-PDZ domains, and a guanylate kinase domain. However, WW domain replaces the characteristic SH3 domain present in other MAGUK proteins. Different components interacting with these proteins in a complex were identified. MAGI-1 was first identified in mouse, as a protein interacting with K-RasB.3 Three isoforms were identified and named MAGI-1a, MAGI-1b and MAGI-1c, of 1139, 1171 and 1374 amino acids, respectively. MAGI-2 was initially identified in rat, as a protein interacting with N-methyl-D-aspartate receptors (NMDA-R) and neuronal cell adhesion proteins, and was named S-SCAM.4 Three isoforms of S-SCAM were identified, of 1277, 1113 and 1053 amino acids length, respectively.5 MAGI-3 (also termed SLIPR) was identified in a two hybrid screening as a protein interacting with the tumor suppressor PTEN,6 and Receptor Tyrosine Phosphatase β (RPTPβ).7 The overall homology among the MAGI proteins, especially regarding the structural domains, is high.

Sigma® has developed anti peptide antibodies that specifically recognize MAGI-1, MAGI-2 and SLIPR/MAGI-3. They are carefully tested by immunoblotting, and are able to distinguish between the three proteins.

Specific recognition of MAGI isoforms by anti MAGI antibodies

Figure 2. Specific recognition of MAGI isoforms by anti MAGI antibodies



Figure 3. Anti ALIPR/MAGI-3





  1. Anderson, J.M., Curr. Biol., 6, 382-384 (1996).
  2. Fanning, A..S., and Anderson, J.M., Curr. Biol., 6, 1385-1388 (1996).
  3. Dobrosostakaya, I., et al, J. Biol. Chem., 272, 31589-31597 (1997).
  4. Hirao, K. et al., J. Biol. Chem., 273, 21105-21110 (1998).
  5. Hirao, K. et al., J. Biol. Chem., 275, 2966-2972 (2000).
  6. Wu, Y., et al., J. Biol. Chem., 275, 21477-21485 (2000).
  7. Adamsky, K. et al., J. Cell Sci., In press (2003).


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