Glycoprotein Ib and glycoprotein IX in human platelets are acylated with palmitic acid through thioester linkages

Journal Article · Thu Jun 15 04:00:00 EDT 1989 · J. Biol. Chem.; (United States)

OSTI ID:5934760

Muszbek, L; Laposata, M

The glycoprotein (GP) Ib-IX complex is a major component of the platelet membrane which mediates adhesion of platelets to exposed subendothelium. GP Ib is a heterodimer with a large alpha chain (Mr = 135,000-145,000) and small beta chain (Mr = 22,000-27,000) linked by a disulfide bond(s). GP Ib is bound in a noncovalent 1:1 complex with GP IX (Mr = 17,000-22,000). We labeled isolated human platelets with (3H) palmitate or surface-labeled platelet membrane glycoproteins with sodium periodate-(3H)sodium borohydride and immunoprecipitated the GP Ib-IX complex from radiolabeled platelet lysates using a mouse monoclonal antibody (SZ.1) which recognizes the intact complex. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitates from (3H)palmitate-labeled platelets revealed two radiolabeled bands under reducing conditions at 24 and 19 kDa and two bands under nonreducing conditions at 170 and 19 kDa. As demonstrated by the parallel analysis of immunoprecipitates from periodate-(3H)sodium borohydride-labeled platelets, the (3H)palmitate-labeled bands obtained under reducing conditions corresponded to GP Ib beta and GP IX and the ones obtained under nonreducing conditions to intact GP Ib and GP IX, respectively. Using alkaline methanolysis followed by high pressure liquid chromatography analysis of the methanolysis products, we demonstrated that the radioactivity associated with the GP Ib-IX complex from (3H)palmitate-labeled platelets was, in fact, covalently bound (3H)palmitate in ester linkage to protein. The protein-fatty acid linkage was also disrupted by hydroxylamine at neutral pH. Thus, this study demonstrates that GP Ib beta and GP IX in human platelets are both fatty acid-acylated with palmitate through thioester linkages.

• Research Organization: Univ. of Pennsylvania School of Medicine, Philadelphia (USA)
• OSTI ID: 5934760
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 264:17; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACYLATION
ADHESION
ANIMALS
ANTIBODIES
BIOASSAY
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD PLATELETS
BODY FLUIDS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
CHROMATOGRAPHY
COMPLEXES
ELECTROPHORESIS
GLYCOPROTEINS
HEXADECANOIC ACID
IMMUNOASSAY
IN VITRO
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIQUID COLUMN CHROMATOGRAPHY
MAMMALS
MAN
MATERIALS
MEMBRANES
MICE
MOLECULAR WEIGHT
MONOCARBOXYLIC ACIDS
MONOCLONAL ANTIBODIES
ORGANIC ACIDS
ORGANIC COMPOUNDS
PRIMATES
PROTEINS
RODENTS
SEPARATION PROCESSES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES