Interaction of lactogenic hormones with the soluble extracellular domain of prolactin receptors.
Two variants of rabbit prolactin receptor extracellular domain (rbPRLR-ECD) were prepared using insect/baculovirus (amino acids 1-198) and E. coli (amino acids 4-210) expression systems. Bovine PRLR-ECD (bPRPL-ECD amino acids 1-210) and human growth hormone receptor ECD (hGHR-ECD amino acids 1-246) were also prepared using E. coli expression system. All four proteins were purified as monomers with > 95% homogeneity. Their affinity for various lactogenic and somatogenic hormones was determined by binding assays. The stoichiometry of complex formation with these hormones was studied by gel filtration on a Superdex 75 column, and bioactivity was determined by in vitro bioassays. The results summarized in this paper indicate that, in contrast to hGHR-ECD, in which the ability to form a 2:1 complex with hGH is indicative of the biological activity of the hormone, the ability or inability of prolactin and placental lactogen to form 2:1 complexes with rb or bPRLR-ECD cannot predict their biological activity. This conclusion does not preclude however, hormone- or antibody-induced dimerization of the membrane-embedded receptor.
Gertler
A
A
Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel.
Bignon
C
C
Staten
N R
NR
Sakal
E
E
Tchelet
A
A
Krivi
G G
GG
Djiane
J
J
D000818:Animals; D002417:Cattle; D004926:Escherichia coli / Q000235:genetics; D005110:Extracellular Space / Q000378:metabolism*; D006801:Humans; D010928:Placental Lactogen / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D011817:Rabbits; D011981:Receptors, Prolactin / Q000235:genetics / Q000378:metabolism*; D011986:Receptors, Somatotropin / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D011981:Receptors, Prolactin; D011986:Receptors, Somatotropin; D011993:Recombinant Fusion Proteins; D011388:Prolactin; D010928:Placental Lactogen