• Home
  • Search Results
  • Ropporin, a sperm-specific binding protein of rhophilin, that is localized in the fibrous sheath of sperm flagella.

Ropporin, a sperm-specific binding protein of rhophilin, that is localized in the fibrous sheath of sperm flagella.

Journal of cell science (1999-12-11)
A Fujita, K Nakamura, T Kato, N Watanabe, T Ishizaki, K Kimura, A Mizoguchi, S Narumiya

The small GTPase Rho; functions as a molecular switch that regulates various cellular processes such as cell adhesion, motility, gene expression and cytokinesis. We previously isolated several putative Rho; targets including rhophilin which bound selectively to the GTP-bound form of Rho;. Rhophilin is expressed highly in testis and is localized specifically in sperm flagella. The presence of a PDZ domain at the carboxy terminus of rhophilin suggested that rhophilin works as an adaptor molecule. To test this hypothesis, we employed a yeast two hybrid system using the rhophilin PDZ domain as a bait, and screened a mouse testis cDNA library. We isolated several positive clones containing the same insert. The open reading frame of the cDNA encoded a novel protein of 212 amino acids designated as ropporin from a Japanese word 'oppo' (the tail). The amino-terminal 40 amino acid sequence of ropporin showed high homology to that of the regulatory subunit of type II cAMP-dependent protein kinase, which is involved in dimerization and binding to A-kinase anchoring proteins. Consistently, a yeast two hybrid assay and gel filtration of recombinant ropporin indicated that ropporin dimerizes through this domain. Deletion analysis indicated that the carboxy-terminal four amino acids are essential for binding of ropporin to rhophilin, and ropporin and RhoV14 coprecipitated in the presence of rhophilin in vitro. Northern blot analysis showed that ropporin is exclusively expressed in testis, and induced at the late stage of spermatogenesis. This induction paralleled that of rhophilin. Immunocytochemistry using anti-ropporin antibody showed that ropporin is localized in the principal piece and the end piece of sperm flagella. Electronmicroscopy revealed that ropporin is mostly localized in the inner surface of the fibrous sheath while rhophilin is present in the outer surface of the outer dense fiber. These results suggest that rhophilin and ropporin may form a complex in sperm flagella.

Product Number
Product Description

Anti-RHPN1 antibody produced in mouse, purified immunoglobulin, buffered aqueous solution
Anti-RHPN1 antibody produced in rabbit, affinity isolated antibody
Anti-RHPN1 antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution, Ab2

Social Media

LinkedIn icon
Twitter icon
Facebook Icon
Instagram Icon


Research. Development. Production.

We are a leading supplier to the global Life Science industry with solutions and services for research, biotechnology development and production, and pharmaceutical drug therapy development and production.

© 2021 Merck KGaA, Darmstadt, Germany and/or its affiliates. All Rights Reserved.

Reproduction of any materials from the site is strictly forbidden without permission.