Viral Proteins in Cell Fusion(MEMBRANE PROTEINS IN CELLULAR INTERACTIONS)

概要

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F (fusion) and HANA (hemagglutinin and neuraminidase) glycoproteins of HVJ (Sendai virus) were purified and characterized. The NH_2-terminal hydrophobic region of the F_1 (larger) subunit of F (fusion)-glycoprotein seems to be required for the hemolytic and cell fusion-inducing activity of the virus for the following reasons. (1) Selective splitting off of a 2,500-3,500 dalton segment from the NH_2-terminal region of F_1 by chymotrypsin or thermolysin resulted in inactivation of the biological activities of HVJ. (2) At least a part of this region may be exposed to the surrounding medium, since it is preferentially iodinated and is easily split by aminopeptidase M, chymotrypsin, and thermolysin. Tryptic digestion, which does not remove the NH_2-terminal region but produce nicking of F_1 subunit to sub fragments F_<1a> (larger one) and F_<1b> (smaller one), resulted in substantial structural changes evidenced by circular dichroism measurement and iodindation by lactoperoxidase method. Trypsin-digested F seems to have the NH_2-terminal hydrophbic region burried within hydrophbic interior of the protein (or in the lipid bilayers). Based on thses and other results, we propose a hypothesis featuring direct interaction of the hydrophbic region with the lipid bilayers of the target-cell membrane as an important step in fusion reactions between the viral envelope and cell membranes.
東海大学の論文
1982-06-14