Expression of human placental G proteins during pregnancy.

Objective:Regulatory guanine nucleotide-binding proteins (G proteins) play key roles in the stimulus-response coupling of many important biological systems. Recent studies from our laboratory suggest a functional role for many G proteins in the human placenta. However, the expression of these proteins has not yet been reported. Therefore, the aims of this investigation were to identify the expression of placental G protein alpha subunits in human placenta, and to study their level of variation during pregnancy.Methods:Western and Northern blot analyses were performed on membrane protein and mRNA preparations, respectively, of human placentas from the first (7-11 weeks), second (16-19 weeks), and third (term) trimesters.Results:The autoradiographs of both proteins and mRNA showed differential expression of placental G proteins during pregnancy. Thus, the relative levels of Gαi2 and Gαi3 subunits were highest during the first trimester, whereas to differences were observed between second-trimester and term ...