Biological activities of glycosylated and nonglycosylated porcine prolactin

K. H. Young, W. C. Buhi, N. Horseman, J. Davis, R. Kraeling, D. Linzer, F. W. Bazer*

*Corresponding author for this work

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Nonglycosylated and glycosylated porcine prolactin (PRL) were separated using concanavalin A-Sepharose CL-6B column chromatography and tested for mitogenic and lactogenic activities, as well as immunoaffinity and receptor binding characteristics compared to total (nonseparated) porcine PRL. Mitogenic activity, using Nb2 lymphoma cells, was 4- and 50-fold greater (P < 0.01) for total PRL than nonglycosylated and glycosylated PRL, respectively. Glycosylated PRL had 64% higher (P < 0.05) lactogenic activity than nonglycosylated or total PRL. In a homologous radioimmunoassay (RIA), displacement was greatest for total, followed by the nonglycosylated and glycosylated forms of PRL. Competitive inhibition of porcine [125I(total) PRL by radioinert total, nonglycosylated and glycosylated PRL in a homologous radioreceptorassay (RRA), indicated similar Ka values for total and nonglycosylated PRL, but different receptor numbers, while radioinert glycosylated PRL had a higher Ka, but bound fewer receptors. Therefore, glycosylated porcine PRL has greater lactogenic activity and higher binding affinity despite decreased mitogenicity, while nonglycosylated PRL had characteristics similar to total PRL. Results from the homologous RRA and the Nb2 assay suggest that both forms of PRL are necessary to achieve biological effects similar to those for total PRL. The two forms of PRL may have individual and collective effects, while changes in the ratio between these forms may influence physiologically diverse effects of PRL on target tissues.

Original languageEnglish (US)
Pages (from-to)155-162
Number of pages8
JournalMolecular and Cellular Endocrinology
Volume71
Issue number2
DOIs
StatePublished - Jun 18 1990

Keywords

  • (Pig)
  • Nb2 lymphoma cell
  • Prolactin
  • Radioreceptor assay
  • glycosylated

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology

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