Publication Date


Document Type


First Advisor

Gasser, Kenneth W.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Exocytosis; Pancreas--Secretions


The present study sought to establish the presence of rab3B, a small molecular weight G protein, and determine its role in the promotion of secretion in exocrine pancreatic cells. Specifically, the goal of the study was to determine whether rab3B is located on zymogen granule membranes and whether the protein is involved in the regulation of fusion between zymogen granule and pancreatic apical plasma membrane. Using a rab3B antibody, Western blots of zymogen granule membrane fractions revealed the presence of a rab3B isoform. Measurements of granule K+ transport showed that ATP inhibited the transport in a dose-dependent manner and that inhibition was overridden by addition of mastoparan, a known GTPase-activating factor. Mastoparan also enhanced the rate of membrane fusion by 153% over controls. These experiments also suggested that the endogenous granule K+ transport pathway is associated with the enhanced fusion rate because mastoparan failed to stimulate fusion in KCI-free solutions. The results of the immunoblotting and the ability of mastoparan to stimulate K+ transport and fusion suggest that a small molecular weight G protein represented by rab3B is present in secretory granules and may play a role in promoting granule K+ transport-mediated exocytosis in pancreatic secretion.


Includes bibliographical references (pages [64]-71)


viii, 71 pages




Northern Illinois University

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