IDENTIFICATION OF A NOVEL MEMBER OF THE TGF-BETA SUPERFAMILY HIGHLY EXPRESSED IN HUMAN PLACENTA

While conducting a gene discovery effort targeted to transcripts of th e prevalent and intermediate frequency classes in placenta throughout gestation, we identified a novel member of the TGF-beta superfamily th at is expressed at high levels in human placenta. Hence, we named this factor 'Placental Transforming Growth Factor Beta' (PTGFB). The full- length sequence of the 1.2-kb PTGFB mRNA has the potential of encoding a putative pre-pro-PTGFB protein of 295 amino acids and a putative ma ture PTGFB protein of 112 amino acids. Multiple sequence alignments of PTGFB and representative members of all TGF-beta subfamilies evidence d a number of conserved residues, including the seven cysteines that a re almost invariant in all members of the TGF-beta superfamily. The si ngle-copy PTGFB gene was shown to be composed of only two exons of 309 bp and 891 bp, separated by a 2.9-kb intron. The gene was localized t o chromosome 19p12-13.1 by fluorescence in-situ hybridization. Norther n analyses revealed a complex tissue-specific pattern of expression an d a second transcript of 1.9 kb that is predominant in adult skeletal muscle. Most importantly, the 1.2-kb PTGFB transcript was shown to be expressed in placenta at much higher levels than in any other human fe tal or adult tissue surveyed. (C) 1997 Elsevier Science B.V.