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 00:00:00 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), Vol. 87:2; ISSN 0027-8424
• Country of Publication: United States
• Language: English

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