The Platelet-derived Growth Factor-inducible KC Gene Encodes a Secretory Protein Related to Platelet α-Granule Proteins

Abstract

A full length cDNA clone of the platelet-derived growth factor-inducible KC gene has been isolated, sequenced, and expressed in COS cells. Both sequence analysis and expression studies indicate that KC encodes a secretory protein. Sequence analysis shows that, furthermore, the protein encoded by KC belongs to a growing superfamily of inducible proteins with a common ancestral linkage to the platelet alpha-granule proteins, platelet factor 4, and connective tissue-activating peptide III. A computer-generated phylogenetic tree documents interrelationships between KC and six additional members of this peptide superfamily. The KC gene is, in all probability, the murine homologue of a human gene termed "gro." By extension, the KC protein is the murine counterpart of the protein encoded by the gro gene. The gro protein corresponds to a factor described as "melanoma growth-stimulating activity."