EXPRESSION OF A KINASE-DEFECTIVE EPH-LIKE RECEPTOR IN THE NORMAL HUMAN BRAIN

We have identified a human Eph-family protein, HEP, gene located in hu man chromosomal region 7q33-->q35. The deduced amino acid sequence sha red primary structural properties of Eph-family receptor tyrosine kina ses. However, six invariant amino acids such as a lysine in the ATP-bi nding site and an aspartic acid in the phosphotransfer site of a conse rved catalytic domain were substituted with other amino acid residues in HEP, Thus, no intrinsic tyrosine kinase activity was detectable in the catalytic domain expressed in CHO-KI cell transfectants, Although most kinase-defective mutants of growth factor receptors have been rep orted as pathogenic receptors, its transcript was abundantly expressed in normal human adult tissues. A 135-kDa HEP protein was expressed in the human brain as much as in CHO-K1 cells transfected with a HEP cDN A expression vector. HEP is the first description of a kinase-defectiv e Eph-family protein expressed abundantly in normal human tissues. (C) 1997 Academic Press.