Location of sequences within rotavirus SA11 glycoprotein VP7 which direct it to the endoplasmic reticulum.

Abstract

The Simian 11 rotavirus glycoprotein VP7 is directed to the endoplasmic reticulum (ER) of the cell and retained as an integral membrane protein. The gene coding for VP7 predicts two potential initiation codons, each of which precedes a hydrophobic region of amino acids (Hi and H2) with the characteristics of a signal peptide. Using the techniques of gene mutagenesis and expression, we have determined that either hydrophobic domain alone can direct VP7 to the ER. A protein lacking both hydrophobic regions was not transported to the ER. Some polypeptides were directed across the ER membrane and then into the secretory pathway of the cell.For a variant retaining only the Hi domain, secretion was cleavage dependent, since an amino acid change which prevented cleavage also stopped secretion. However, secretion of two other deletion mutants lacking Hi and expressing truncated H2 domains was unaffected by this mutation, suggesting that these proteins were secreted without cleavage of their NH2-terminal hydrophobic regions or secreted after cleavage at a site(s) not predicted by current knowledge.

Serological and genomic characterization of L338, a novel equine group A rotavirus G serotype

“…These changes suggest that the function of the hydrophobic HI region (aa 6 to 23) is probably inhibited by glycosylation at aa 20, and that such an inhibition of function has a significant effect on the viability of the virus. The precise role of the H1 region is unknown, although this region can act as a signal peptide for transport to the endoplasmic reticulum (Whitfield et al, 1987).…”

Biosynthesis and morphogenesis of group C rotavirus in swine testicular cells

“…The results from the morphogenesis studies and previous deletion experiments [15,19,27] on group A vp 7 indicate that the ER retention signal of vp 7 is structurally dependent rather then sequence dependent. The formation of viroplasms with assembly of single-shelled particles budding into ER cisternae leading to the formation of intermediate, enveloped particles as well as the intriguing metamorphosis of this particle into the mature virus particle within the ER cisternae appear therefore to be features shared with group A rotavirus.…”

“…In spite of the lack of amino acid homology between the residues associated with ER retention in vp 7 of groups A and C rotaviruses [ 15,16,19,27], group C rotavirus matures and is retained in the ER. The results from the morphogenesis studies and previous deletion experiments [15,19,27] on group A vp 7 indicate that the ER retention signal of vp 7 is structurally dependent rather then sequence dependent.…”

“…The morphological studies were undertaken not only because of the absence of homology between groups A and C rotaviruses within the vp 7 region associated with ER retention [15,16,19,27] but also because a counterpart in group C rotavirus to the trans-ER NS 28 receptor of group A rotavirus not has been recognized [11].…”

Monoclonal antipeptide antibodies recognize epitopes upon VP4 and VP7 of simian rotavirus SA11 in infected MA104 cells

“…The relative reduction of specific immunofluorescence shows the degree of specific inhibition by corresponding and noncorresponding peptide respectively (RER) [26] where it triggers the endogenous budding process. The nonstructural glycosylated membrane protein NS28 seems to guide both the mature singleshelled particles and the cytoplasmic VP4 to the endoplasmic reticulum membrane [15] where NS28 and VP7 lodges [1,3,20,30]. During the budding process, VP7 is added to the intermediate particle.…”