ISOLATION AND CHARACTERIZATION OF A CDNA FOR HUMAN, MOUSE, AND RAT FULL-LENGTH STEM-CELL GROWTH-FACTOR, A NEW MEMBER OF C-TYPE LECTIN SUPERFAMILY

cDNA encoding stem cell growth factor (SCGF; 245 aa), a novel human gr owth factor for primitive hematopoietic progenitor cells, has been pre viously reported (Hiraoka, A,, Sugimura, A., Seki, T., Nagasawa, T., O hta, N., Shimonishi, M., Hagiya, M. and Shimizu, S. Proc. Natl. Acad. Sci. USA 94, 7577-7582, 1997). Here we report the cloning and characte rization of a full-length SCGF cDNA. This protein consists of 323, 328 and 328 aa in the human, murine and rat forms, the latter two of whic h share 85.1% and 83.3% aa identity, and 90.4% and 90.4% aa similarity to the human protein, respectively. Because the newly identified huma n clone encodes the protein longer by 78 aa than that previously ident ified, we term the longer clone as hSCGF-alpha and the shorter one as hSCGF-beta. The computer-assisted homology search reveals that SCGF is a new member of the C-type lectin superfamily, and that SCGF shows th e greatest homology to tetranectin among the members of the family (27 .2-33.7% aa identity and 46.0-53.6% aa similarity). SCGF transcripts a re detected in spleen, thymus, appendix, bone marrow and fetal liver. Fluorescent in situ hybridization mapping indicates that the SCGF gene is located on chromosome 19 at position q13.3 for human form and on c hromosome 7 at position B3-B5 for murine form, which are close to flk- 2/flt3 ligand and interleukin-ll genes of both human and murine specie s. (C) 1998 Academic Press.