MOUSE HEPATITIS-VIRUS RECEPTOR ACTIVITIES OF AN MHVR MPH CHIMERA AND MHVR MUTANTS LACKING N-LINKED GLYCOSYLATION OF THE N-TERMINAL DOMAIN/

Mouse hepatitis virus binds to the N-terminal domain of its receptor, MHVR, a murine biliary glycoprotein with four immunoglobulin-like doma ins (G. S. Dveksler, M. N. Pensiero, C. W. Dieffenbach, C. B. Cardelli chio, A. A. Basile, P. E. Elia, and K. V. Holmes, Proc. Natl. Acad. Sc i. USA 90:1716-1720, 1993). A recombinant protein with only the anchor ed N-terminal domain was not a functional receptor, but a recombinant protein with the N-terminal domain of MHVR linked to the second and th ird immunoglobulin-like domains and anchor from the mouse poliovirus r eceptor homolog, mph, was a functional receptor for mouse hepatitis vi rus. The native four-domain MHVR has 16 potential N-linked glycosylati on sites, including three on the N-terminal domain. Recombinant protei ns lacking each one of these three sites or all three of them were fun ctional receptors. Thus, glycosylation of the N-terminal domain is not required, but a glycoprotein longer than the N-terminal domain is req uired for virus receptor activity.