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United States Department of Agriculture

Agricultural Research Service

Title: The carboxyl-terminus of cytochrome b5 confers endoplasmic reticulum specificity by preventing spontaneous insertion into membranes

Author
item Henderson, Matthew
item Andrews, David
item Hwang, Yeen
item Mullen, Robert
item Dyer, John

Submitted to: Biochemistry and Cell Biology
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2006
Publication Date: 12/1/2006
Citation: Henderson, M.P., Andrews, D.W., Hwang, Y.T., Mullen, R.T., Dyer, J.M. 2006. The carboxyl-terminus of cytochrome b5 confers endoplasmic reticulum specificity by preventing spontaneous insertion into membranes (abstract). Biochemistry and Cell Biology 84(6):1084-1084.

Interpretive Summary:

Technical Abstract: The molecular mechanisms that determine the correct subcellular localization of proteins targeted to membranes by tail-anchor sequences are poorly defined. Previously, we showed that two isoforms of tung tree (Vernicia fordii) tail-anchored cytochrome b5 (Cb5) target specifically to endoplasmic reticulum (ER)membranes both in vivo and in vitro (Hwang, Pelitre, Henderson, Andrews, Mullen, 2004. Plant Cell. 16:3002-3019). Here we examine the targeting of various tung Cb5 fusion proteins and truncation mutants to purified intracellular membranes in vitro in order to assess the importance of the charged carboxyl-terminal sequence in targeting to specific membranes. Removal of the carboxyl-terminal sequence from tung Cb5 proteins resulted in efficient binding to both ER and mitochondria. Results from organelle competition, liposome-binding and membrane proteolysis experiments demonstrated that removal of the carboxyl-terminal sequence results in spontaneous insertion of tung Cb5 proteins into lipid bilayers. Our results indicate that the carboxyl-terminal sequences from plant Cb5 proteins provide ER specificity by preventing spontaneous insertion into incorrect subcellular membranes.

Last Modified: 06/22/2017
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