Lysophosphatidic acid acyltransferase (LPAAT) catalyzes the addition of fatty acyl moieties to the sn-2 position of the glycerol backbone of lysophosphatidic acid in triglyceride biosynthesis. In this study, we have cloned, sequenced, and characterized the bovine and ovine LPAAT cDNA. Both encode proteins of 287 amino acids with molecular masses of 32 and 31.9 kDa, respectively, differing only by a single amino acid residue. The bovine and ovine LPAAT are predicted to be transmembrane enzymes localized to the endoplasmic reticulum. We also characterized the sequence and genomic organization of the bovine LPAAT gene. The gene consists of seven exons and six introns, spanning a 7.5-kb distance. With the use of a whole genome radiation hybrid panel, we localized the bovine LPAAT to the central region of chromosome 23.