Thrombolamban, the 22-kDa platelet substrate of cyclic AMP-dependent protein kinase, is immunologically homologous with the Ras family of GTP-binding proteins

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.87.2.758· OSTI ID:6719520

White, T E; Fischer, T H; White, II, G C ^[1]; Lacal, J C; Reep, B ^[2]; Lapetina, E G ^[3]

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1. Univ. of North Carolina, Chapel Hill (USA)
2. Burroughs Wellcome, Inc., Research Triangle Park, NC (USA)
3. Univ. of North Carolina, Chapel Hill (USA) Burroughs Wellcome, Inc., Research Triangle Park, NC (USA)

Platelet inhibition by agents that increase intracellular levels of cAMP is associated with cAMP-dependent phosphorylation of specific intracellular proteins, including a membrane-associated 22-kDa microsomal protein called thrombolamban. In view of recent studies suggesting that platelets also contain 22-kDa GTP-binding proteins that are homologous with ras-encoded p21 proteins, the present work was undertaken to examine the possibility that thrombolamban and the Ras-like proteins were the same. Platelet microsomes were labeled with ({gamma}-{sup 32}P)ATP and the labeled proteins were examined by autoradiography of sodium dodecyl sulfate/polyacrylamide gels. On Western blots of both one-dimensional and two-dimensional gels, thrombolamban immunoreacted with M90, a monoclonal antibody that recognizes the GTP-binding domain of Ras p21 proteins, but not with Y13-259, a monoclonal antibody that recognizes another domain and is specific for Ras proteins. Overlay experiments with unlabeled platelet microsomes demonstrated numerous low molecular weight proteins that bound ({alpha}-{sup 32}P)GTP, although none could be identified as thrombolamban. Finally, thrombolamban was immunoprecipitated by M90. These studies show that thrombolamban is a low molecular weight protein that is immunologically related to the Ras family of GTP-binding proteins.

• OSTI ID: 6719520
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (USA) Vol. 87:2; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMP
ANTIBODIES
AROMATICS
ATP
AUTORADIOGRAPHY
AZAARENES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BLOOD COAGULATION FACTORS
BLOOD PLATELETS
BODY FLUIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
COAGULANTS
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTROPHORESIS
ENZYMES
GUANOSINE
HEMATOLOGIC AGENTS
HETEROCYCLIC COMPOUNDS
IMMUNOLOGY
ISOTOPES
LABELLING
LIGHT NUCLEI
MATERIALS
MICROSOMES
MONOCLONAL ANTIBODIES
NUCLEI
NUCLEOSIDES
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHORYLATION
PHOSPHOTRANSFERASES
PRECIPITATION
PROTEINS
PURINES
RADIOISOTOPES
RIBOSIDES
RIBOSOMES
SEPARATION PROCESSES
SUBSTRATES
TRANSFERASES