Incorporation of myristate and palmitate into the sheep reticulocyte transferrin receptor: evidence for identical sites of labeling

Journal Article · Mon Aug 01 00:00:00 EDT 1988 · Arch. Biochem. Biophys.; (United States)

DOI:https://doi.org/10.1016/0003-9861(88)90321-9· OSTI ID:6838495

Adam, M; Turbide, C; Johnstone, R M

The ability of sheep reticulocytes and plasma membranes isolated from them to incorporate fatty acids into the transferrin receptor has been examined using both (3H)palmitate and (3H)myristate. Both fatty acids, when incorporated into the transferrin receptor, can be released by treating the protein with 1 M hydroxylamine at pH 7.0. After treatment of the 3H-acylated receptor with borohydride, an 3H-labeled alcohol is released, suggesting that the receptor-bound fatty acid is in thioester linkage. With both (3H)myristate and (3H)palmitate, Cleveland maps from immunoprecipitates of the transferrin receptor labeled in intact cells and isolated membranes show that identical peptides are labeled. No evidence was obtained for qualitatively different labeling with the two fatty acids. In intact reticulocytes, incorporation of (3H)palmitate into the transferrin receptor is approximately 3.5 times greater than the incorporation of (3H)myristate from equivalent concentrations of the labeled fatty acids. However, in isolated reticulocyte plasma membranes, there is much less difference between palmitate and myristate incorporation (with ATP) or between their acyl-CoA derivatives. The reason for the discrepancy between cells and membranes is unknown but may be due to the presence in intact cells of more than one enzyme for activating the fatty acids. Acylation of the receptor in isolated plasma membranes is fourfold greater with the CoA derivatives than with the free fatty acids. The fatty acid activating enzyme(s) as well as the acyltransferase(s) appear to be membrane bound in reticulocytes.

• Research Organization: McGill Univ., Montreal (Canada)
• OSTI ID: 6838495
• Journal Information: Arch. Biochem. Biophys.; (United States), Vol. 264:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
HEXADECANOIC ACID
METABOLISM
TETRADECANOIC ACID
TRANSFERRIN
RECEPTORS
ACYLATION
CELL MEMBRANES
CHYMOTRYPSIN
CYSTEINE
PROTEINS
RETICULOCYTES
SERINE PROTEINASES
SHEEP
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS
AMINO ACIDS
ANIMALS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
DOMESTIC ANIMALS
ENZYMES
ERYTHROCYTES
GLOBULINS
GLOBULINS-BETA
HYDROLASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
MEMBRANES
METALLOPROTEINS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PEPTIDE HYDROLASES
RUMINANTS
THIOLS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques