Faculty Collaboration Database

Mutation of serine 90 to glutamic acid mimics phosphorylation of bovine prolactin. J Biol Chem 1995 Nov 17;270(46):27661-5

Date

11/17/1995

Pubmed ID

7499231

DOI

10.1074/jbc.270.46.27661

Scopus ID

2-s2.0-0028832856 (requires institutional sign-in at Scopus site)   61 Citations

Abstract

Phosphorylated prolactin has been identified and isolated from bovine pituitaries. The biological activity of this phosphoprotein is severely reduced in comparison with nonphosphorylated prolactin. The sites of phosphorylation are serines 26, 34, and 90, and the stoichiometry is 1:1:10, respectively. In this report, the phosphoserine residues have been individually replaced with glutamic acid in recombinant methionyl bovine prolactins in order to mimic phosphorylation at each site. Substitution of glutamic acid for serine at positions 26, 34, and 90 reduced protein helical contents by 10, 6, and 14%, respectively. UV absorbances for S26E and S34E bovine prolactins were blue-shifted, similar to the biological isolates of phosphorylated bovine prolactin, but the biological activities of the S26E and S34E mutants (ED50 values of 16.3 and 18.8 pM, respectively) were similar to that of wild-type prolactin (ED50 value of 18.6 pM) in the Nb2 rat lymphoma assay. S90E bovine prolactin had the greatest reduction in helical content but showed similar UV and fluorescent spectra to the wild-type bovine prolactin. The biological activity of S90E bovine prolactin (ED50 value of 672 pM) was reduced to an activity similar to that of phosphorylated bovine prolactin. The data indicate that the phosphorylation of serine 90 is responsible for the reduction in biological activity.

Author List

Maciejewski PM, Peterson FC, Anderson PJ, Brooks CL

Author

Francis C. Peterson PhD Professor in the Biochemistry department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acid Sequence
Animals
Biological Assay
Cattle
Circular Dichroism
Glutamic Acid
Lymphoma
Mutagenesis, Site-Directed
Phosphoproteins
Phosphorylation
Point Mutation
Prolactin
Protein Conformation
Rats
Recombinant Proteins
Serine
Spectrometry, Fluorescence