THE CHARACTERIZATION AND LOCALIZATION OF THE MOUSE THYMOPOIETIN LAMINA-ASSOCIATED POLYPEPTIDE-2 GENE AND ITS ALTERNATIVELY SPLICED PRODUCTS

Thymopoietins (Tmpos) are a group of ubiquitously expressed nuclear pr oteins, with sequence homology to lamina-associated polypeptide 2 (LAP 2). Here we report the isolation and characterization of seven mouse T mpo mRNA transcripts named Tmpo alpha, beta, beta', gamma, epsilon, de lta, and zeta. The alpha, beta, and gamma Tmpo cDNA clones are the mou se homologs of the previously characterized human alpha, beta, and gam ma TMPOs, respectively, whereas Tmpo epsilon, delta, and zeta are nove l cDNAs. Additionally, the mouse Tmpo gene was cloned and characterize d. It is a single-copy gene organized in 10 exons spanning similar to 22 kb, which encodes all of the described Tmpo cDNA sequences, located in the central region of mouse chromosome 10, The almost identical ge nomic organization between the human and mouse genes, and the novel al ternatively spliced mouse transcripts, led us to reanalyze the human T MPO gene. The human beta-specific domain was found to be encoded by 3 exons designated 6a, 6b, and 6c and not by a single exon as described previously. These findings suggest that there may be more human transc ripts than currently recognized, The possible involvement of the new g rowing family of Tmpo proteins in nuclear architecture and cell cycle control is discussed.