Surface and internal galactosyl receptors are heterooligomers and retain this structure after ligand internalization or receptor modulation

Journal Article · Tue Jul 10 04:00:00 EDT 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00479a015· OSTI ID:6229711

Herzig, M C.S.; Weigel, P H ^[1]

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1. Univ. of Texas Medical Branch, Galveston (USA)

The authors have developed a specific chemical affinity reagent for the hepatic galactosyl receptor (GalR) by derivatizing asialoorosomucoid (ASOR) with the homobifunctional N-hydroxysuccinimide (NHS) ester cross-linker disuccinimidyl suberate. NHS-ASOR cross-links with 30-50% efficiency to the three GalR subunits, designated rat hepatic lectins (RHL) 1, 2, and 3. Here, they examined the subunit structure of both surface and internal receptors of two functionally distinct GalR subpopulations, designated state 1 or state 2 GalR. Freshly isolated cells, referred to as state 1 cells, kept at 4{degree}C express only active state 1 GalR on their surface. When these cells are equilibrated at 37{degree}C, they then express both state 1 GalR and state 2 GalR on their surface. These cells are referred to as state 1,2 cells. After incubation at 4{degree}C with NHS-{sup 125}I-ASOR, surface or internal GalR of state 1 cells or of state 1,2 cells incorporated {sup 125}I-ASOR into all three RHL subunits. As analyzed by autoradiography of SDS-PAGE, radiolabeling was identical for all conditions and was in a ratio of 1:1:1 for RHL 1:2:3. Native GalR structure was also examined by first cross-linking nonradiolabeled NHS-ASOR at 4{degree}C to surface or internal receptors of state 1 or state 1,2 hepatocytes. Internalized GalR had the same ratio of free to cross-linked subunits as noninternalized GalR. Depletion of ATP either before or after cross-linking GalR to NHS/ASOR also did not alter the ratio of free to cross-linked RHL subunits. They conclude that the surface and internal GalR of the two functionally distinct GalR populations have the same heterooligomeric subunit composition and that this GalR structure persists following endocytosis or ATP depletion.

• OSTI ID: 6229711
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:27; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ATP
CHEMICAL REACTIONS
CROSS-LINKING
DERIVATIZATION
ELECTROPHORESIS
ESTERS
GLYCOPROTEINS
LIGANDS
MEMBRANE PROTEINS
MOLECULAR STRUCTURE
NUCLEOTIDES
ORGANIC COMPOUNDS
POLYMERIZATION
PROTEINS
RECEPTORS