Retention by the endoplasmic reticulum of rotavirus VP7 is controlled by three adjacent amino-terminal residues.
AUTOR(ES)
Maass, D R
RESUMO
The rotavirus outer capsid glycoprotein, VP7, is an endoplasmic reticulum (ER) membrane-associated glycoprotein in both infected and transfected cells. It was previously demonstrated in this laboratory and by others that both the cleaved signal sequence (H2) and the first NH2-terminal 61 amino acids of VP7 are sufficient and necessary for ER retention of this molecule. Using site-specific mutagenesis and transfection techniques, we show that residues Ile-9, Thr-10, and Gly-11 were specifically necessary for ER retention. These results further define the ER retention sequence of VP7 and demonstrate that conservative changes, apparently innocuous in only three adjacent amino acids, can lead to major solubility and compartmentalization changes. It was found that placement of the first 31 mature NH2-terminal residues of VP7, in addition to the cleaved ER translocation signal sequence, was sufficient to retain the enzymatically active chimeric alpha-amylase in the ER; this enzyme is normally secreted. Deletions of the residues Ile-9, Thr-10, and Gly-11 within the amylase chimera containing 31 VP7 amino acids resulted in secretion of enzymatically active protein. It was also observed that the residues of VP7 presented in certain chimeras were able to abolish alpha-amylase enzymatic activity. These chimeras are presumably misfolded since it was demonstrated by pulse-chase experiments that these molecules are degraded in the ER. We surmise that a favorable conformation is necessary for retention since ER retention and activity of the chimeras depend on the primary sequence context.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=236297Documentos Relacionados
- Membrane binding and endoplasmic reticulum retention sequences of rotavirus VP7 are distinct: role of carboxy-terminal and other residues in membrane binding.
- Two forms of VP7 are involved in assembly of SA11 rotavirus in endoplasmic reticulum.
- Location of sequences within rotavirus SA11 glycoprotein VP7 which direct it to the endoplasmic reticulum.
- An Endoplasmic Reticulum Retention Signal Located in the Extracellular Amino-terminal Domain of the NR2A Subunit of N-Methyl-d-aspartate Receptors*
- Human Parathyroid Hormone: Amino-Acid Sequence of the Amino-Terminal Residues 1-34