title: Comparison of in vitro bioactivity of chicken prolactin and mammalian lactogenic hormones.
abstract: Recombinant chicken prolactin, expressed in Escherichia coli as an unfolded protein, was successfully refolded and purified to homogeneity as a monomeric protein. Its biological activity was evidenced by its ability to interact with rabbit prolactin receptor extracellular domain and stimulate prolactin receptor-mediated proliferation in three cell types possessing mammalian prolactin receptors. Chicken prolactin activity in those assays was 20-100-fold lower than that of mammalian lactogenic hormones, likely due to lower affinity for mammalian prolactin receptors and not to improper refolding, because in two homologous bioassays, chicken prolactin activity was equal to or higher than that of ovine prolactin and the CD spectra of chicken and human prolactin were almost identical. Our results using seven mammalian lactogenic hormones from five species in three bioassays revealed the major role of species specificity in testing biological activity in vitro. Heterologous bioassays may be misleading and homologous assays are strongly recommended for predicting the activity of species-specific lactogenic hormones in vivo.
authors.affiliation: Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100, Israel; Department of Animal Physiology and Endocrinology, University of Agriculture in Krakow, Al Mickiewicza 24/28, 30-059 Krakow, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Ocłoń
authors.affiliation: Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100, Israel; Department of Animal Physiology and Endocrinology, University of Agriculture in Krakow, Al Mickiewicza 24/28, 30-059 Krakow, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Leśniak-Walentyn
authors.affiliation: Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Gili
authors.initials: G
authors.lastname: Solomon
authors.affiliation: Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Shpilman
authors.affiliation: Department of Animal Physiology and Endocrinology, University of Agriculture in Krakow, Al Mickiewicza 24/28, 30-059 Krakow, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Hrabia
authors.affiliation: Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100, Israel. Electronic address: arieh.gertler@mail.huji.ac.il.
authors.forename: Arieh
authors.initials: A
authors.lastname: Gertler
mesh_terms: D000818:Animals; D002645:Chickens / Q000378:metabolism*; D006801:Humans; D008322:Mammals; D011388:Prolactin / Q000378:metabolism*; D011817:Rabbits; D012756:Sheep; D013045:Species Specificity
chemical_list: D011388:Prolactin
keywords: Bioactivity; Chicken; Prolactin; Recombinant; Species specificity