A heptad motif of leucine residues found in membrane proteins can drive self-assembly of artificial transmembrane segments - PubMed (original) (raw)

. 1999 Apr 2;274(14):9265-70.

doi: 10.1074/jbc.274.14.9265.

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A heptad motif of leucine residues found in membrane proteins can drive self-assembly of artificial transmembrane segments

R Gurezka et al. J Biol Chem. 1999.

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Abstract

Specific interactions between alpha-helical transmembrane segments are important for folding and/or oligomerization of membrane proteins. Previously, we have shown that most transmembrane helix-helix interfaces of a set of crystallized membrane proteins are structurally equivalent to soluble leucine zipper interaction domains. To establish a simplified model of these membrane-spanning leucine zippers, we studied the homophilic interactions of artificial transmembrane segments using different experimental approaches. Importantly, an oligoleucine, but not an oligoalanine, se- quence efficiently self-assembled in membranes as well as in detergent solution. Self-assembly was maintained when a leucine zipper type of heptad motif consisting of leucine residues was grafted onto an alanine host sequence. Analysis of point mutants or of a random sequence confirmed that the heptad motif of leucines mediates self-recognition of our artificial transmembrane segments. Further, a data base search identified degenerate versions of this leucine motif within transmembrane segments of a variety of functionally different proteins. For several of these natural transmembrane segments, self-interaction was experimentally verified. These results support various lines of previously reported evidence where these transmembrane segments were implicated in the oligomeric assembly of the corresponding proteins.

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