Isolation and mapping of a human lung-specific gene, TSA1902, encoding a novel chitinase family member

Using differential display technique, we have isolated a novel human gene e xpressed specifically in the lung. Two forms of the gene, designated TSA190 2, were transcribed by alternate mRNA splicing. The transcribed mRNAs, term ed TSA1902-L and TSA1902-S, putatively encode proteins of 368 and 315 amino acids, respectively, which show high similarity to human chitotriosidase p rotein. The N-terminal region of TSA1902-L protein contains the conserved a ctive site residues (DXXDXDXE) of the catalytic center of various chitinase s which are essential for chitinase activity. The deduced protein sequence of TSA1902-S, however, does not possess this active site, with the N-termin al 54 amino acids present in TSA1902-L protein having been deleted. Both pr oteins lacked the secretory sequence of N-termini and, judging from the hyd ropathy profile, may be soluble proteins in the cytoplasm. Chromosomal mapp ing by radiation hybrid analysis localized this gene to the chromosome 1p13 .1-p21.3. (C) 1999 Elsevier Science B.V. All rights reserved.