Faculty Collaboration Database

rap1B, a cAMP-dependent protein kinase substrate, associates with the platelet cytoskeleton. J Biol Chem 1990 Nov 15;265(32):19405-8

Date

11/15/1990

Pubmed ID

2123187

Scopus ID

2-s2.0-0025224154 (requires institutional sign-in at Scopus site)   82 Citations

Abstract

rap1B is a member of the ras superfamily of low molecular weight GTP binding proteins which constitutes a focal point of GTP and cAMP signal transduction systems. Like other members of this superfamily, rap1B is membrane-associated in resting platelets, presumably through polyisoprenylation. The studies presented here were undertaken to determine the subcellular changes in rap1B localization during cell activation. Activated and unactivated platelets were fractionated by Triton X-100 lysis followed by differential centrifugation to obtain a 10,000 x g cytoskeleton fraction, a 100,000 x g membrane skeleton fraction, and a 100,000 x g supernatant fraction containing solubilized proteins. In unactivated platelets, rap1B was present in the 100,000 x g supernatant fraction. In contrast, in platelets activated with 1 unit/ml alpha-thrombin or with the calcium ionophore, A23187, rap1B was quantitatively recovered in the 10,000 x g cytoskeleton fraction. rap1B was absent from the 100,000 x g fraction containing the membrane skeleton and could not be detected in the 100,000 x g supernatant containing cytosolic proteins and solubilized membrane components. These results indicate that rap1B associates with the cytoskeleton during cell activation.

Author List

Fischer TH, Gatling MN, Lacal JC, White GC 2nd

Author

Gilbert C. White MD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acid Sequence
Blood Platelets
Blotting, Western
Calcimycin
Cell Fractionation
Cell Membrane
Cytoskeleton
GTP-Binding Proteins
Humans
Molecular Sequence Data
Molecular Weight
Platelet Activation
Protein Kinases
Thrombin
rap GTP-Binding Proteins