Isolation and Characterzation of p160.2, a Signal Transducing Protein Downstream of Jak3.

Nonreceptor tyrosine kinase Jak3, which binds to intracellular domain of interleukin-2 receptor gamma subunit (IL-2Rgamma), plays an important role in IL-2 function. To find downstream signal transducer of Jak3, the N-terminal region JH3-JH7 of Jak3 was used as a baitg to screen a cDNA library by using the yeast two-hybrid system. One real true clone was obtained out of 10(5) cotransformants. Sequencing indicated that it encoded a p160.2 protein fragment which consisted of 399 amino acid residues. Further results showed that the p160.2 fragment merely bound to the intact JH3-JH7 through its C-terminal. Northern blot revealed that human p160.2 shared homology with monkey p160.2, but was different from mouse p160.2; and p160.2 was widely expressed in various tissues.