%0 Thesis
%9 Doctoral
%A Teo, Mabel
%B Institute of Neurology
%D 1994
%F discovery:10098872
%I UCL (University College London)
%T Purification and functional characterization of brain and recombinant chimaerin, a p21rac GTPase activating protein
%U https://discovery.ucl.ac.uk/id/eprint/10098872/
%X n-chimaerin is a GAP for the ras-related p21rac. A 45 kDa brain protein  (p45) immune reactive to anti-n-chimaerin polyclonal antibodies had selective  p21 rac GAP activity, using an overlay assay. p45-chimaerin was purified 400-  fold from rat brain by column chromatography. Tryptic peptides contained  sequences identical to that predicted from α2-chimaerin cDNA, a splice variant  encoding a divergent N-terminal with a SH2 domain. Thus, p45-chimaerin  probably corresponds to SH2-containing (α2) chimaerin. A 35 kDa p21rac GAP  (p35) detected in detergent soluble membrane fractions, immunoreactive to  chimaerin antiserum was likely to represent n-chimaerin (α1-chimaerin). Diverse  GAPs for the rho/rac family were present in the brain; p45-chimaerin was widely  distributed in brain regions except cerebellum, and was present in both  membrane and cytosolic fractions.  Both native and recombinant a2-chimaerin exhibited p21rac GAP activity  in solution, which was stimulated by phosphatidylserine with a synergistic effect  by phorbol esters. GAP activity of α2-chimaerin was unaffected by its SH2  domain. In contrast to α1-chimaerin, α2-chimaerin bound more phorbol ester  in the presence of phosphatidylinositol than of phosphatidylserine. α2-Chimaerin  was phosphorylated by PKC and PKA in vitro. Brain proteins interacting with  α2-chimaerin were detected using 32P-labelled PKC phosphorylated chimaerin.  A 60 kDa protein interacting with the SH2 domain of α2-chimaerin was purified;  peptide sequences showed it to be novel. Two peptides had similarity to the  consensus sequences of a MAP kinase substrate and a SH2 binding domain.  These data suggest that α2-chimaerin plays a physiological role in neuronal  signal transduction involving SH2-linked receptor/tyrosine kinase and p21rac  signalling pathways.
%Z Thesis digitised by ProQuest.