HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Gorewit, R. C. Articles by Tucker, H. A. Search for Related Content PubMed PubMed Citation Articles by Gorewit, R. C. Articles by Tucker, H. A.

Comparison of Binding Proteins of Glucocorticoids in Mammary Tissue and in Blood Sera from Lactating Cows¹

Animal Reproduction Laboratory, Department of Dairy Science, Michigan State University, East Lansing 48824

ABSTRACT

Supernatant fractions (700 X g) isolated from homogenates of mammary tissue slices from three lactating Holstein cows (slices previously incubated with [hydrogen-3] Cortisol for 1 h at 37 C) were electrophoresed on 7% polyacrylamide gels. The majority of radioactivity was in a protein(s) 2.5 to 3 cm from the origin whereas bovine serum incubated with [hydrogen-3] Cortisol showed the majority of radioactivity in a protein 5 to 6 cm from the origin. N,N-diethylamino-ethyl cellulose chromatography of 700 X g supernatant fluids from three lactating cows revealed that [hydrogen-3] Cortisol was associated with a protein component that eluted with .3 M potassium phosphate, pH 8.0. In contrast, [hydrogen-3] Cortisol bound to bovine sera eluted as two protein components with .05 and .1 M potassium phosphate, pH 8.0. Approximate molecular weights determined from gel filtration (four lactating cows) and sucrose density studies (two lactating cows) were estimated to be 2.5 X 10⁵ to 3 X 10⁶ for the 700 X g mammary receptor of Cortisol and 6 X 10⁴ to 8 X 10⁴ for the primary protein which binds Cortisol in serum. We conclude that lactating bovine mammary tissue contains a protein(s) capable of binding tritiated Cortisol which is unique from the corticosteroid binding proteins of blood.

¹ Published with the approval of the Director of the Michigan Agricultural Experiment Station as Journal Article No. 7542. This research was supported in part by USPHS Grant HD-05750.

² Department of Animal Science, Cornell University, Ithaca, NY 14853.