G Substrate (GSBS)

The protein encoded by this gene is found primarily in cerebellar Purkinje cells, where it functions as a protein phosphatase inhibitor. The encoded protein is a substrate for cGMP-dependent protein kinase. An allele of this gene was discovered that increases susceptibility to hypercholesterolemia. Two transcript variants encoding different isoforms have been found for this gene. The deduced amino acid sequence of human G-substrate contained 2 putative phosphorylation sites (thr68 and thr119) with amino acid sequences that were identical to those reported for rabbit G-substrate. G-substrate mRNA was expressed almost exclusively in the cerebellum as a single transcript. In vitro translation products of the cDNA showed an apparent molecular mass of 24 kD on SDS/PAGE, which was close to that of purified rabbit G-substrate (23 kD).