Date Written

2016

Document Type

Honors Paper

Degree Name

Biochemistry and Molecular Biology-BS

Department

Biochemistry and Molecular Biology

Advisor

Dr. John T. Tansey

First Committee Member

Dr. John T. Tansey

Second Committee Member

Dr. Jeffrey S. Lehman

Third Committee Member

Dr. Karen Steigman

Keywords

Splice Variant, Perilipin 5, Lipid Droplets, Lipolysis

Subject Categories

Biochemistry, Biophysics, and Structural Biology

Abstract

Lipid droplets, or LDs, are very important and dynamic organelles in cells. LDs are stores

of fat for use in metabolism, membrane construction, and signaling. Dysfunction of lipid droplet formation or breakdown can lead to many health risks, such as atherosclerosis and diabetes. Lipid droplet regulation occurs primarily via a dynamic and complex coat of proteins on the surface of the droplet. This work sought to characterize a novel variant, or new protein, derived from the sequence of the parent chain of perilipin-5, which we have termed perilipin-5B. Perilipin-5 is a member of the perilipin family of lipid droplet coat proteins and is found primarily in tissues that break down fats for energy, such as heart, liver, and skeletal muscle. Perilipin-5B is thought to play a crucial role in lipid droplet degradation due to its close association to lipolytic enzymes. By using various protein characterization methods, such as western blot, immunofluorescence, and mass spectrometry, we sought to show the presence of this protein and its pattern of expression. Using RNA based techniques, such as RT-PCR, and DNA base techniques, such as restriction digests and TA Cloning, we sought to elucidate a possible function of the protein and show that perilipin-5B arose from a splice variant, rather than a post-translational modification. We found that perilipin-5B expression parallels that of perilipin-5, that is, it is found in oxidative tissues. Immunofluorescence showed that perilipin-5B is unable to bind lipid droplets, but does form distinct puncta. RT-PCR showed that multiple messages exist that include intron 8 of the perilipin-5 gene. Together, this suggests that perilipin-5B is a splice variant of perilipin-5 found in oxidative tissues that is unable to bind to lipid droplets.

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