Cloning and functional analysis of MCH1: A mammalian homolog of the yeast adenylyl cyclase-associated protein, CAP.
Item
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Title
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Cloning and functional analysis of MCH1: A mammalian homolog of the yeast adenylyl cyclase-associated protein, CAP.
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Identifier
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AAI9605689
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identifier
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9605689
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Creator
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Zelicof, Audrey.
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Contributor
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Adviser: Jeffrey E. Gerst
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Date
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1995
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Cell
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Abstract
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The RAS pathway of the budding yeast S.cerevisiae has been well characterized using genetic and biochemical means. This signaling cascade is distinguished by the RAS-dependent activation of adenylyl cyclase which ultimately results in enhanced cell growth and proliferation.;One of the requirements for RAS-mediated stimulation of adenylyl cyclase activity is the presence of the CAP protein. CAP consists of three domains; an amino terminus, a carboxyl terminus and a proline-rich stretch that connects the two regions. The amino terminus mediates RAS signaling through adenylyl cyclase while the carboxyl terminus regulates cellular morphology in response to environmental extremes. In contrast to the amino-terminus, the function of the carboxyl-terminal domain is not well understood. Thus, the objectives of this work were to clarify the role of the carboxyl terminus of CAP and, furthermore, to examine if CAP and its functions have been conserved in mammals.;In order to identify a mammalian homolog of CAP, or genes that encode functionally similar proteins, we transformed a rat embryo cDNA library into a strain deficient for CAP. We then looked for proteins which could suppress phenotypes incurred due to the loss of the carboxyl terminus. This strategy yielded a mammalian homolog of CAP, which we named MCH1 (Mammalian Cap Homolog 1). Structurally, MCH1 is similar to the yeast CAP proteins with the greatest similarity in the proline-rich and carboxyl-domains.;Functional characterization of MCH1 reveals that it is capable of both actin binding and dimerization. Furthermore, these properties are conserved between CAP and MCH1, and are mediated by separate regions on the carboxyl terminus. The actin binding properties of MCH1 and CAP, described here, define a role for these proteins in actin-cytoskeleton regulation, although, the functions mediated through protein dimerization have not yet been determined.;The bifunctional nature of CAP suggests that it couples proliferative signals with changes in cell growth and proliferation. Many of these effects are mediated through the carboxyl-terminal domain. Here, we have demonstrated two novel properties of the carboxyl terminus of CAP and, furthermore, have shown that these functions remain conserved between yeast and mammals.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
