Membrane-bound proteins of Japanese encephalitis virus-infected chick embryo cells

The seven Japanese encephalitis virus specific polypeptides found in infected chick embryo cells were all bound to membranes. None were completely released from the membranes by treatment with neutral salt, alkaline salt, or dilute detergent, but two of them were partially released by both the neutral and alkaline salts. The polypeptides were released or attacked by trypsin at unequal rates and in the sequence: NV-5≥ NV-4 > V-3. NV-5 was released as a relatively undegraded soluble polypeptide, NV-4 was extensively degraded, and V-3 was degraded but part of its trypsinderived fragment (TF-2) remained membrane bound. We suggest that the three largest viral polypeptides are bound in such a manner that the larger the polypeptide, the more exposed and superficial it is. Treatment of virions with trypsin produced low molecular weight material and three discrete polypeptide fragments, probably all derived from the large virion envelope protein V-3; two (TF-1 and TF-3) had electrophoretic mobilities similar to the two naturally occurring nonvirion virus-specified polypeptides, NV-1 and NV-3.