MAPPING THE MIDKINE FAMILY OF DEVELOPMENTALLY-REGULATED SIGNALING MOLECULES

Midkine (Mdk) and heparin-binding neurotrophic factor (Hbnf)/pleiotrop hin (Ptn) comprise the Midkine family of developmentally regulated sig naling molecules. We have determined the chromosomal localization of t hese genes in the mouse by use of single-strand conformation polymorph isms (SSCPs), which facilitated the typing of Mdk and Hbnf alleles in recombinant inbred (RI) strains and interspecific back-crosses. Mappin g was performed relative to other cloned genes, as well as simple sequ ence length polymorphisms (SSLPs) in the interspecific backcrosses. Md k maps to mouse Chromosome (Chr) 2, linked to the Hoxd gene cluster. H bnf maps to proximal mouse Chr 6, linked to the Cftr and Cpa genes. Co mparative mapping of human MDK and HBNF employing species-specific pol ymerase chain reaction (PCR) primers and human monochromosomal somatic cell hybrids assigns MDK to human Chr 11 and HBNF to human Chr 7q32-q ter.