Date of Award

5-2004

Document Type

Thesis

Department

Chemistry

First Advisor

John Coleman

Second Advisor

Allen Davis

Abstract

In this thesis, I will discuss the study I conducted from June 2, 2003 to July 31, 2003 at the University of Oklahoma Health Sciences Center Dean A. McGee Eye Institute, facilitated by Dr. Michael Elliott, funded by the Undergraduate Biomedical Education Program at Langston University, expressing and purifying GST-Cav~olin fusion proteins on a large-scale. Caveolins are the principle constituents of caveolae. Caveolae are flask-shaped invaginations of the plasma membrane. Caveolae are most abundant in endothelial cells, fibroblasts, and myocytes (Smart et al. 1999). These structures participate in three main areas of cell physiology: endocytosis (Henley et al. 1999), cholesterol traffic (Razani et al. 2000) and signal transduction (Okamoto et al. 1998). Currently, three different forms of caveolins are known: caveolin-1 (or VIP21), caveolin-2, and caveolin-3 (or M-caveolin).

Caveolin family members share three characteristic properties: detergent insolubility at low temperatures, selfoligomerization and incorporation into low-density Triton-insoluble fractions enriched in caveolae membranes (Song et al. 1997). Other functions for caveolins include lipid transport, membrane trafficking, and tumor suppression and tumor suppression (reviewed in Okamoto et al. 1998; Liu et al. 2002).

Vision involves the conversion of light into electrochemical signals that are processed by the retina and then sent to and interpreted by the brain (see Figure 1.1). The process of converting light into electrochemical signals begins when the protein, rhodopsin, absorbs light within the retina. Photoexcitation of rhodopsin causes the cytoplasmic surface of the protein to become active. In the active state, rhodopsin then binds and activates transducin, a G-protein composed of three subunits a, p, and y. The activated transducin protein separates into GTP-a while GTP-P and GDP-r sections remain coupled. Ta activates phosphodiesterase (PDE), 7 which, in turn, hydrolyzes cyclic GMP. The decrease of cyclic GMP concentration closes the cyclic GMP-gated channels on the photoreceptor cells, causing a shift in the cell's electric potential and a neural impulse to the brain.

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