Oral Biology Research Profiles

R. P. Bhullar
B.Sc. (McMaster), Ph.D. (Manitoba)
Department Head, Professor


GTP-Binding Proteins and Platelet Function Heterotrimeric GTP-binding proteins are an intermediary in linking cell surface receptors to effectors inside the cell. The ras p21 related or low molecular mass GTP-binding proteins are important in regulating various intracellular membrane trafficking processes including, regulated secretion. Platelets are small anucleated disc shaped cell of the blood that are derived from megakaryocytes in the bone marrow.

In response to an appropriate external stimuli platelets can release the contents of their storage granules into the extracellular medium to influence blood vessel function. Platelet dysfunction has been suggested to play a role in the development of various occulsive vascular diseases (e.g. thrombosis, atherosclerosis, stroke).

The research in our laboratory has focussed on defining the role of low molecular mass GTP-binding proteins and their interacting partner proteins in platelet physiology. Various biochemical (e.g. protein purification, protein-protein interaction), molecular biology (e.g. expression of proteins in E.coli and mammalian systems, site-directed mutagenesis), immunology (e.g. Western blotting, immunofuorescence) and cell culture techniques are being employed to characterize and define the function of GTP-binding proteins in the platelet secretory process.

A comprehensive understanding of platelet secretory process at the molecular level may provide for new target(s) that could facilitate the development of new therapeutic approaches that will be of use in the control of platelet function in various diseased conditions.

Supported by the Heart and Stroke Foundation of Canada.

Relevant publications

  • Bhullar, R.P. and Seneviratne, H.D. (1996) Characterization of human platelet GTPase activating protein for the Ral GTP-binding protein. Biochim. Biophys. Acta 1311:181-188.
  • Bhullar, R.P. (1996) Expression of a 24 kDa GTP-binding protein (Gn24) is increased in lovastatin treated human erythroleukemia cells. Molec. Cell. Biochem. 156:59-67.
  • Mark, B.L., Jilkina, O. and Bhullar, R.P. (1996) Association of Ral GTP-binding protein with human platelet dense granules. Biochem. Biophys. Res. Comm. 225:40-46.
  • Bhullar, R.P. (1994) Effect of lovastatin on the expression of low molecular mass GTP-binding proteins in human erythroleukemia cells. J. Cell. Physiol. (submitted).
  • Jilkina, O. and Bhullar, R.P. (1996) Generation of antibodies specific for ralA and ralB GTP-binding proteins and determination of their concentration and distribution in human platelet. Biochim. Biophys. Acta 1314:157-166.
  • Bhullar, R.P. (1997) Small molecular weight G-proteins: characterization and significance. In: G protein methods and protocols: role of G-proteins in psychiatric and neurological disorders (Boulton, A.A., Baker, G.B. and Mishra, R.K. (eds)). Published by the Humana Press Inc. Neuromethods 31:pp. 29-51.