The mouse Gh/tissue transglutaminase gene (Tgm2), coding a dual-function protein that both binds guanosine triphosphate (GTP) and catalyzes the posttranslational modification of proteins by transamidation of glutamine residues, has been cloned. Sequence analysis of Tgm2 and comparison with the TGase sequences 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 similarity 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 Gh gene, TGM2. Tgm2 maps to the distal region of mouse chromosome 2, a region syntenic to human chromosome 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.