MITOGEN-INDUCIBLE SIPA1 IS MAPPED TO THE CONSERVED SYNTENIC GROUPS OFCHROMOSOME-19 IN MOUSE AND CHROMOSOME 11Q13.3 CENTROMERIC TO BCL1 IN HUMAN

Sipa1, previously called Spa1, is transcriptionally induced in the mur ine lymphoid cells following mitogenic stimulation and encodes a prote in with a domain related to Rap1 GTPase activating protein (Rap1GAP) a t the N-terminus and to PEST sequences followed by a leucine zipper mo tif at the C-terminus. Herein mouse genomic Si,pal, which consisted of 16 exons, was cloned. Gene linkage analysis using (BXD) recombinant i nbred strains indicated that Sipa1 was mapped to the most centromeric region of chromosome 19 syntenic with the long arm of human chromosome II. Human SIPA1 cDNA exhibited a striking homology to that of mouse t hroughout the entire region, with the overall identity being 90% at th e amino acid level. Human genomic clones, which hybridized with both m ouse and human SIPA1 cDNA but not with RAP1GAP cDNA, were then isolate d. Fluorescence in situ hybridization (FISH) analysis using the human genomic clones indicated that SIPA1 was indeed mapped to chromosome 11 q13, most Likely to the 11q13.3 subregion. It was further indicated by double-color FISH that SIPA1 was located in the centromeric neighborh ood of CCND1/PRAD1, a presumed BCL1 oncogene. (C) 1997 Academic Press