The A and B forms of the chicken progesterone receptor arise by alternate initiation of translation of a unique mRNA.
In order to establish the origin of the A and B proteins of the chicken progesterone receptor we have expressed its cDNA in vivo in heterologous cells and in vitro in reticulocyte cell lysates. The A and B proteins were expressed from a single cDNA both in heterologous receptor negative cells and in a cell-free system. Both proteins bind progesterone and are indistinguishable from chick oviduct authentic A and B proteins in terms of size, immunoreactivity and hormone binding properties. Truncated mRNA's which lack the receptor B protein translation signal are capable of generating the receptor A protein by initiation of translation at a second internal start site. We conclude from these data that the chicken progesterone receptor A and B proteins arise most likely by alternate initiation of translation from a single mRNA transcript.
Conneely
O M
OM
Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.
Maxwell
B L
BL
Toft
D O
DO
Schrader
W T
WT
O'Malley
B W
BW
D000818:Animals; D002645:Chickens; D005786:Gene Expression Regulation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D014158:Transcription, Genetic
D012333:RNA, Messenger; D011980:Receptors, Progesterone