Sequence, genomic organization, and chromosomal localization of the human LPAP (PTPRCAP) and mouse CD45-AP/LSM-1...

Human LPAP (lymphocyte phosphatase associated phosphoprotein) and its mouse homologue, CD45-AP (CD45 associated protein) or LSM-1, represent 32- and 30-kDa transmembrane phosphoproteins that noncovalently associate with the tyrosine phosphatase CD45, a key molecule involved in T- and B-lymphocyte activation. Here we report the isolation and sequencing of genomic clones of the human and mouse genes. LPAP (HGMW-approved symbol PTPRCAP) maps to human chromosome 11q13, distal to the BCL-1 breakpoint, and mouse CD45-AP/LSM-1 maps to Chromosome 19B. Both genes span 3 kb and consist of two exons that are separated by a 1.2-kb intron. The promoter regions do not contain TATA boxes, but possess consensus transcriptional initiator sequences that have also been described for other TATA-less genes. The genomic sequences also provide a genetic basis for two different cDNAs (termed CD45-AP and LSM-1, respectively) that have been described in the mouse system.