A NEURONAL PROTEIN-TYROSINE-PHOSPHATASE INDUCED BY NERVE GROWTH-FACTOR

A new protein tyrosine phosphatase (PC12-PTP1) was identified in nerve growth factor (NGF) treated PC12 cells, The mRNA level of PC12-PTP1 i s increased 9-fold over the initial 8 h of NGF treatment and then decr eases dramatically after 24 h of treatment, In rat brain, three transc ripts corresponding to 1.5, 2.6, and 3.0 kilobases (kb) in size are de tected by Northern blot analysis. Although the 1.5- and 2.6-kb transcr ipts are present in brain and other tissues, the 3-kb transcript is ex clusively expressed in brain and the expression of this transcript alo ne increases following NGF treatment, PC12-PTP1 is a non-receptor prot ein tyrosine phosphatase (PTP) with a 50% sequence homology in the pho sphatase domain with several other non-receptor PTPs. PC12-PTP1 fusion protein exhibits tyrosine phosphatase activity, and in vitro translat ion of the PC12-PTP1 transcript produces a major protein of 39 kDa. Th e data presented suggest that NGF regulates the expression of PC12-PTP 1 during periods of neuronal growth and differentiation.