MOLECULAR DETERMINANTS OF GOLGI RETENTION IN THE PUNTA-TORO VIRUS G1 PROTEIN

The G1 glycoprotein of Punta Toro virus, a member of the bunyavirus fa mily, accumulates in the Golgi complex when it is expressed from clone d cDNA, We previously reported that the information necessary for Gels retention of the G1 protein is located within the transmembrane domai n and a portion of the cytoplasmic domain adjacent to the transmembran e domain (Matsuoka, Y., Chen, S.-Y., and Compans, R,W, (1994) J, Biol, Chem, 269, 22565-22573), To determine the features of the amino acid sequence motif required for Gels retention, we have introduced mutatio ns including truncations and point mutations in the transmembrane and the cytoplasmic domains and examined the cellular localization of the expressed mutant proteins, The results from truncation mutants indicat e that the crucial information appears to be located within the first 10 amino acids of the cytoplasmic domain, Within this region, mutation of a proline residue yielded a protein that was transported to the ce ll surface, A protein was also expressed on the cell surface when one of the threonine residues in the transmembrane domain was changed to l eucine, Thus the transmembrane domain may have a supportive role in Go lgi retention, possibly by promoting protein interactions through hydr oxylated side chains. (C) 1996 Academic Press, Inc.