TY  - UNPB
N1  - Thesis digitised by ProQuest.
PB  - UCL (University College London)
A1  - Teo, Mabel
AV  - public
TI  - Purification and functional characterization of brain and recombinant chimaerin, a p21rac GTPase activating protein
M1  - Doctoral
Y1  - 1994///
UR  - https://discovery.ucl.ac.uk/id/eprint/10098872/
ID  - discovery10098872
N2  - 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 ?2-chimaerin cDNA, a splice variant
encoding a divergent N-terminal with a SH2 domain. Thus, p45-chimaerin
probably corresponds to SH2-containing (?2) chimaerin. A 35 kDa p21rac GAP
(p35) detected in detergent soluble membrane fractions, immunoreactive to
chimaerin antiserum was likely to represent n-chimaerin (?1-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 ?2-chimaerin was unaffected by its SH2
domain. In contrast to ?1-chimaerin, ?2-chimaerin bound more phorbol ester
in the presence of phosphatidylinositol than of phosphatidylserine. ?2-Chimaerin
was phosphorylated by PKC and PKA in vitro. Brain proteins interacting with
?2-chimaerin were detected using 32P-labelled PKC phosphorylated chimaerin.
A 60 kDa protein interacting with the SH2 domain of ?2-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 ?2-chimaerin plays a physiological role in neuronal
signal transduction involving SH2-linked receptor/tyrosine kinase and p21rac
signalling pathways.
ER  -