Isolation, Sequence and Expression of a Novel Mouse-Brain cDNA, mIA-2, and Its Relatedness to Members of the Protein Tyrosine Phosphatase Family

摘要: This study describes the isolation of a putative transmembrane protein tyrosine phosphatase (PTP), mIA-2, from mouse brain cDNA library. The encodes 979 amino acids containing unique extracellular domain and single intracellular catalytic domain. Expression mIA-2 was found primarily in central nervous system neuroendocrine cells. sequence shares high degree homology with its human counterpart (92% identity), especially domain, which shows 99.3% identity between two species. In both IA-2, several substitutions were highly conserved regions including an Ala to Asp substitution core sequence. Bacterial expression glutathione S-transferase fusion showed that had no enzyme activity conventional substrates such as Raytide, myelin basic protein, angiotensin, RR-src pNpp. When tested total tyrosine-phosphorylated cellular proteins isolated on anti-phosphotyrosine antibody column, it also little, if any, activity. These findings suggest is new member PTP family either has very narrow substrate specificity perhaps requiring post-translational modification for or still unknown biological function.