Organization and Chromosomal Mapping of Mouse G h /Tissue Transglutaminase Gene (Tgm2) 1 Nisha Nanda,* , † Siiri E. Iismaa,* Neal G. Copeland,‡ Debra J. Gilbert,‡ Nancy Jenkins,‡ Robert M. Graham,* , † ,2 and Pramod Sutrave* ,3 *Molecular Cardiology Unit, Victor Chang Cardiac Research Institute, 384 Victoria Street, Darlinghurst, New South Wales 2010, Australia; †School of Biochemistry and Molecular Genetics, University of New South Wales, New South Wales 2054, Australia; and ‡Mammalian Genetics Laboratory, ABL-Basic Research Program, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, Maryland 21702 Received February 1, 1999, and in revised form February 26, 1999 The mouse G h /tissue transglutaminase gene (Tgm2), coding a dual-function protein that both binds guanosine triphosphate (GTP) and catalyzes the post- translational modification of proteins by transamida- tion of glutamine residues, has been cloned. Sequence analysis of Tgm2 and comparison with the TGase se- quences of other species allowed correction of several apparent sequencing artifacts in the Tgm2 cDNA. Tgm2 spans approximately 34 kb and has 13 exons and 12 introns. Although the structure of Tgm2 shows sim- ilarity to that of other transglutaminase genes, with introns ranging from 921 bp to > 5 kb, several introns differ considerably in size from those of the human G h gene, TGM2. Tgm2 maps to the distal region of mouse chromosome 2, a region syntenic to human chromo- some 20q containing TGM2. Tgm2 is in the vicinity of two uncloned mouse mutations, diminutive (dm) and blind-sterile (bs). Genomic DNA from dm mice was unavailable; however, Southern blot analysis of bs DNA showed no gross rearrangements of Tgm2. © 1999 Academic Press Key Words: G h ; tissue transglutaminase; gene; map- ping; organization; sequence. The nonheterotrimeric G-protein, G h , is a multifunc- tional protein with both guanosine triphosphatase (GTPase) and transglutaminase (TGase) 4 activities. The molecular mass of G h varies in different species from 74 to 80 kDa and has been shown to mediate intracellular signaling by the  1B - and  1D - but not  1A -adrenergic receptors (1, 2) by coupling to mem- brane-bound phospholipase C (3, 4). G h also couples to the oxytocin receptor (5) and modulates the conduc- tance of the Maxi-K + ion channel in smooth muscle (6). The TGase family of enzymes are thiol- and Ca 2+ -de- pendent acyl transferases that catalyze the formation of an amide bond between the -carboxamide groups of peptide-bound glutamine residues and the primary amino groups in various compounds (7). Six distinct transglutaminases have been described [reviews (8, 9)]. These include the plasma factor XIIIA (fXIIIA) involved in catalyzing formation of the fibrin clot at sites of blood coagulation; keratinocyte TGase (TGase I), which plays a major role in terminal differentiation of epithelia and in the formation of the cornified cell envelope of the epidermis; tissue TGase (TGase II, G h ), which has been implicated in a variety of processes including apoptosis, cell adhesion, and signal trans- duction; epidermal TGase (TGase III), involved in dif- ferentiating epidermal and hair follicle cells; prostate TGase (TGase IV), which, in rodents results in the formation of the copulatory plug through crosslinking of proteins in the seminal vesicle secretion (7); and the enzymatically inactive band 4.2, involved in the cy- toskeletal network. Only the human genes for these TGases have been reported to date. The genomic organization of these 1 Tgm2 GenBank Accession No. AF114266. 2 To whom correspondence should be addressed at Victor Chang Cardiac Research Institute, 384 Victoria Street, Darlinghurst, NSW 2010, Australia. E-mail: b.graham@victorchang.unsw.edu.au. Fax: 612–9295– 8501. 3 Present address: AviGenics Inc., 220 Riverbend Road, Athens, GA 30602. 4 Abbreviations used: TGase, transglutaminase; PCR, polymerase chain reaction; UTR, untranslated region; RFLP, restriction frag- ment length polymorphism. 0003-9861/99 $30.00 151 Copyright © 1999 by Academic Press All rights of reproduction in any form reserved. Archives of Biochemistry and Biophysics Vol. 366, No. 1, June 1, pp. 151–156, 1999 Article ID abbi.1999.1189, available online at http://www.idealibrary.com on