Regulation of ras p21 by GTPase Activating Proteins
This extract was created in the absence of an abstract.
Excerpt
Conversion of active forms of ras p21 to inactive forms is catalyzed by proteins referred to as GTPase activating proteins (GAPs), which stimulate hydrolysis of bound GTP to GDP (Hall 1990; McCormick 1990). In mammalian cells, two distinct types of GAPs have been described. One is a protein of 120,000 daltons that includes regions of homology with nonreceptor tyrosine kinases (SH regions) and is able to interact with tyrosine phosphoproteins in addition to ras p21. This protein will be referred to as p120-GAP. The second is the product of the neurofibromatosis type 1 (NF1) locus, and will be referred to as NF1-GAP. NF1-GAP is predicted to be about 325,000 daltons and appears to be the mammalian homolog of the yeast proteins IRA1 and IRA2 (Ballester et al. 1990; Martin et al. 1990; Xu et al. 1990a,b). Both types of GAPs appear to be expressed ubiquitously (Wallace et al. 1990) and...
