Cloning and expression of two structurally distinct receptor-linked protein-tyrosine phosphatases generated by RNA...

We describe here the first example of RNA processing generating two functional receptor-linked protein-tyrosine phosphatases (PTP) (protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48) that are structurally distinct within their catalytic domains. Two cDNAs, PTP-P1 and PTP-PS, were isolated from rat pheochromocytoma cells, which encode two receptor-linked protein-tyrosine-phosphatases and are produced by alternative splicing and differential use of polyadenylation sites. Both cDNAs share an identical extracellular domain and a single transmembrane domain, but differ within their cytoplasmic regions: PTP-P1 contains two tandem repeated PTPase catalytic domains, whereas PTP-PS contains only the amino-terminal domain. Bacterial expression of PTPase domains of both cDNAs demonstrates that PTP-P1 and PTP-PS contain tyrosine-phosphatase activity. PTP-P1 is encoded by three transcripts of approximately 8, 6, and 4 kilobases, whereas PTP-PS is encoded by a single 4.8-kilobase transcript. PTP-P1 (6 kilobases) and PTP-PS are mainly expressed within the brain and in neuronal and endocrine cells. These data suggest that PTP-P1 and PTP-PS may be involved in neuronal function.