Date of Award

6-2010

Document Type

Union College Only

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Brian Cohen

Language

English

Keywords

receptor, caveolin, mutant, binding, hormone

Abstract

Compartmentalization of signal transducing proteins into membrane microdomains is one explanation as to why cells are capable of producing rapid and efficient signaling responses. These microdomains, or lipid rafts, provide scaffolding for various essential cell signaling molecules to come into close proximity with other effectors. Follicle stimulating hormone receptor (FSHR) is a G-protein coupled receptor shown to localize in lipid rafts, potentially in a subtype of lipid rafts known as caveolae. Previous work in this lab has shown that human FSHR co-immunoprecipitates with caveolin, a scaffolding protein that serves as the molecular marker for caveolae. Presence of a putative caveolin binding motif in the fourth transmembrane domain of hFSHR suggests that the receptor interacts with caveolin at this site; this interaction could prove necessary for hormone binding, signal transduction, or membrane trafficking. To test the role of caveolin interaction with the hFSHR, we created two mutant receptors with point mutations in one of the essential aromatic residues in the caveolin binding domain to a leucine residue. Both mutants were successfully transfected and synthesized in human embryonic kidney cells (HEK 293). Preliminary data suggests that wild-type receptor and mutant receptor with point mutation F481L interacts with caveolin while mutant receptor F489L does not. We have also found that receptor F481L is still capable of binding to hormone with a slightly higher affinity to ligand then wild-type receptor. Mutant receptor F489L is unable to bind to hormone and we have shown that this mutant is not being expressed at the cell surface, suggesting that caveolin may be essential for hFSR’s ability to bind ligand or for trafficking to the cell membrane.

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