Parvins (affixin, actopaxin, CH-ILKBP)

Page updated 9th March '04

A family of actin binding proteins from  the a-actinin super-family, the parvins are so-called because they are small relative to other members of the superfamily ("parvus" latin for small).  The family consists of c42kDa proteins that while sharing the CH actin binding head region, lacks any rod domain (Korenbaum et al, 2001). A number of parvins are known from sequences deposited in various databases especially as EST clones, many have alternate names (table 1). 

a-parvin, which has also been described as CH-ILKBP (Wu & Dedhar, 2001; Tu et al, 2001) and actopaxin (Nikolopoulos & Turner, 2000), is located at the focal contact, some cell -cell adhesion junctions, ruffling membranes and the nucleus (Olski et al, 2000).  The first CH domain of b-parvin binds aPIX (Rosenberger et al, 2003), a Cdc42 and Rac1 guanine nucleotide exchange factor and so activates these G-proteins (Mishima et al, 2004).  b-parvin is also localised at the focal contact and the leading edge of moving cells (Yamaji et al, 2001), and binds ILK (Yamaji et al,2001;2002 ).

References:-

Brakebusch, C. & Fassler, R. (2003) The integrin-actin connection, an eternal love affair. EMBO J. 22, 2324-2333.

Korenbaum, E., Olski, T. M. & Noegel, A. A. (2001) Genomic organization and expression profile of the parvin family of focal adhesion proteins in mice and humans, Gene. 279, 69-79.

Mishima, W., Suzuki, A., Yamaji, S., Yoshimi, R., Ueda, A., Kaneko, T., Tanaka, J., Miwa, Y., Ohno, S. & Ishigatsubo, Y. (2004) The first CH domain of affixin activates Cdc42 and Rac1 through aPIX, a Cdc42/Rac1-specific guanine nucleotide exchanging factor. Genes Cells. 9, 193-204.

Nikolopoulos, S. N. & Turner, C. E. (2000) Actopaxin, a new focal adhesion protein that binds paxillin LD motifs and actin and regulates cell adhesion. J.Cell Biol. 151, 1435-1448.

Olski, T. M., Noegel, A. A. & Korenbaum, E. (2000) Parvin, a 42kDa focal adhesion protein, related to the a-actinin superfamily. J.Cell Sci. 114, 525-538.

Rosenberger, G., Jantke, I., Gal, A. & Kutsche, K. (2003) Interaction of {alpha}PIX (ARHGEF6) with {beta}-parvin (PARVB) suggests an involvement of {alpha}PIX in integrin-mediated signaling. Hum. Mol. Genet. 12, 155-167.

Tu, Y., Huang, Y., Zhang, Y., Hua, Y. & Wu, C. (2001) A new focal adhesion protein that interacts with integrin-linked kinase and regulates cell adhesion and spreading. J. Cell Biol. 153, 585-598.

Wu, C. & Dedhar, S. (2001) Integrin-linked kinase (ILK) and its interactors: a new paradigm for the coupling of extracellular matrix to actin cytoskeleton and signaling complexes.  J. Cell Biol. 155, 505-510.

Yamaji, S., Suzuki, A., Sugiyama, Y., Koide, Y., Yoshida, M., Kananori, H., Mori, H., Ohno, S. & Ishigatsubo, Y. (2001) A novel intergrin-linked kinase-binding protein, affixin, is involved in the early stage of cell-substratum interaction. J Cell Biol. 153, 1251-1264.

Yamaji, S., Suzuki, A., Kanamori, H., Mishima, W., Takabayashi, M., Fujimaki, K., Tomita, N., Fujisawa, S., Ohno, S. & Ishigatsubo, Y. (2002) Possible role of ILK-affixin complex in integrin-cytoskeleton linkage during platelet aggregation, Biochemical and Biophysical Research Communications. 297, 1324-1331.