Identification of a human rasGAP-related protein containing calmodulin-binding motifs.
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Weissbach L, Settleman J, Kalady MF, Snijders AJ, Murthy AE, Yan YX, Bernards A
Identification of a human rasGAP-related protein containing calmodulin-binding motifs.
J Biol Chem. 1994 Aug 12;269(32):20517-21.
- PubMed ID
- 8051149 [ View in PubMed]
- Abstract
Conversion of active GTP-bound Ras to its inactive GDP-bound form is catalyzed by GTPase-activating proteins (GAPs). Two mammalian Ras-specific GAPs, p120GAP and neurofibromin, the product of the NF1 tumor suppressor gene, have been previously described. We report here the identification of a new human cDNA clone, IQGAP1, which predicts a 1657-amino acid protein that displays extensive sequence similarity to the catalytic domain of all previously reported RasGAPs. IQGAP1 is most closely related to the Schizosaccharomyces pombe RasGAP-like protein, Sar1. Sequence similarity to IQGAP1 is seen throughout the entire Sar1 protein. The N-terminal half of IQGAP1, which does not overlap with Sar1, contains six copies of a unique amino acid motif, as well as four so-called IQ motifs. The latter motifs are found in several proteins, including conventional and unconventional myosins, and mediate the interaction with calmodulin and calmodulin-related proteins. Thus, IQGAP1 appears to represent a novel RasGAP-like protein that may link Ras signaling to some calmodulin-mediated process.