Identification of luteinizing hormone-like proteins in the ovine pineal gland.
A chemical analysis was instigated to investigate the identity of the luteinizing hormone (LH)-like immunoactivity present in ovine pineal protein homogenates. Isolation of pineal LH-like material was accomplished using a 0.1 M ammonium sulphate (pH 4.0) extraction followed by anion-exchange chromatography. The resulting 3.0 M ammonium sulphate precipitate containing 70% of the LH-like immunoactivity was refractionated by cation-exchange and Sephadex G-100 chromatography. Analysis of the pattern of recovered LH-like immunoactivity in the Sephadex G-100 eluate indicated the presence of molecular weight (MW) less than 60,000 besides MW 21,000 species of LH-like proteins. Bioactivity was tested in the rat Leydig cell steroidogenesis assay. In terms of steroid production, the activity was associated with the MW 21,000 LH-like proteins only. Further purification by CM-Sephadex chromatography and gel permeation HPLC was conducted in order to determine whether the physicochemical properties of pineal LH-like material represented endogenous LH, synthesized and released by the ovine pituitary. It is concluded by a variety of means, including polyacrylamide gel electrophoresis, and amino acid and carbohydrate analyses, that at least two molecular forms of immunoactive LH-like proteins occur in ovine pineal tissue. The MW 21,000 forms showed much similarity with ovine adenohypophyseal LH or with a complex mixture of its subunits. These observations contribute to the understanding of endocrine-endocrine transducing events that may occur in this organ.
Noteborn
H P
HP
Department of Organic Chemistry, University of Utrecht, The Netherlands.
de Koning
J
J
de Jong
F H
FH
Ebels
I
I
Salemink
C A
CA
D000818:Animals; D001681:Biological Assay; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003429:Cross Reactions; D003911:Dextrans; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005640:Follicle Stimulating Hormone / Q000032:analysis / Q000302:isolation & purification; D005782:Gels; D007986:Luteinizing Hormone / Q000032:analysis / Q000302:isolation & purification*; D008297:Male; D008970:Molecular Weight; D010870:Pineal Gland / Q000737:chemistry*; D010902:Pituitary Gland / Q000737:chemistry; D011863:Radioimmunoassay; D012756:Sheep
D003911:Dextrans; D005782:Gels; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C025614:sephadex