Expression of a Kinase-DefectiveEph-like Receptor in the Normal Human Brain

• Published in: Biochemical and biophysical research communications Vol. 235; no. 3; pp. 487 - 492
• Main Authors: Matsuoka, Hiroshi, Iwata, Nobuko, Ito, Mitsuhiro, Shimoyama, Manabu, Nagata, Aki, Chihara, Kazuo, Takai, Setsuo, Matsui, Toshimitsu
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.06.1997
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1997.6812

We have identified a humanEph-family protein, HEP, gene located in human chromosomal region 7q33→q35. The deduced amino acid sequence shared primary structural properties ofEph-family receptor tyrosine kinases. However, six invariant amino acids such as a lysine in the ATP-binding site and an aspartic acid in the phosphotransfer site of a conserved 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-K1 cell transfectants. Although most kinase-defective mutants of growth factor receptors have been reported 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 cDNA expression vector. HEP is the first description of a kinase-defectiveEph-family protein expressed abundantly in normal human tissues.