Previous Article | Next Article ![]()
Mol. Cell. Biol., Oct 1997, 5707-5718, Vol 17, No. 10
T Chen, BB Damaj, C Herrera, P Lasko and S Richard
Sam68 is a member of a growing family of proteins that contain a single KH
domain embedded in a larger conserved domain of approximately 170 amino
acids. Loops 1 and 4 of this KH domain family are longer than the
corresponding loops in other KH domains and contain conserved residues. KH
domains are protein motifs that are involved in RNA binding and are often
present in multiple copies. Here we demonstrate by coimmunoprecipitation
studies that Sam68 self-associated and that cellular RNA was required for
the association. Deletion studies demonstrated that the Sam68 KH domain
loops 1 and 4 were required for self-association. The Sam68 interaction was
also observed in Saccharomyces cerevisiae by the two-hybrid system. In situ
chemical cross-linking studies in mammalian cells demonstrated that Sam68
oligomerized in vivo. These Sam68 complexes bound homopolymeric RNA and the
SH3 domains of p59fyn and phospholipase Cgamma1 in vitro, demonstrating
that Sam68 associates with RNA and signaling molecules as a multimer. The
formation of the Sam68 complex was inhibited by p59fyn, suggesting that
tyrosine phosphorylation regulates Sam68 oligomerization. Other Sam68
family members including Artemia salina GRP33, Caenorhabditis elegans
GLD-1, and mouse Qk1 also oligomerized. In addition, Sam68, GRP33, GLD-1,
and Qk1 associated with other KH domain proteins such as Bicaudal C. These
observations indicate that the single KH domain found in the Sam68 family,
in addition to mediating protein-RNA interactions, mediates protein-protein
interactions.
Copyright © 1997, American Society for Microbiology
Self-association of the single-KH-domain family members Sam68, GRP33, GLD-1, and Qk1: role of the KH domain
Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, and Department of Oncology, McGill University, Montreal, Quebec, Canada.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»