Sequences within and adjacent to the transmembrane segment of alpha-2,6-sialyltransferase specify Golgi retention.
The glycosyltransferase alpha-2,6-sialyltransferase (ST) is a Type II membrane protein localized to the Golgi apparatus. The first 44 amino acids of this protein were able to specify Golgi retention of a fused marker protein, lysozyme. This section of ST contains a transmembrane segment which serves as a non-cleaved signal anchor. When lysozyme was fused to an equivalent region of a cell surface protein it now appeared on the cell surface. Analysis of chimeras between the two proteins revealed that the transmembrane segment of ST specifies Golgi retention. Furthermore, altering this segment in full-length ST results in the protein accumulating on the cell surface. However, the retaining effect of the transmembrane domain of ST is augmented by the presence of adjacent lumenal and cytoplasmic sequences from ST. If these sequences are spaced apart by a transmembrane domain of the same length as that of ST they too can specify Golgi retention. Thus retention in the Golgi of ST appears to involve recognition of an extended region of the protein within and on both sides of the bilayer.
MRC Laboratory of Molecular Biology, Cambridge, UK.
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Munro
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002678:Chimera; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000235:genetics; D004792:Enzyme Precursors / Q000235:genetics; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000201:enzymology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009113:Muramidase / Q000235:genetics / Q000378:metabolism; D010957:Plasmids; D011233:Precipitin Tests; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D004792:Enzyme Precursors; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012799:Sialyltransferases; D009113:Muramidase; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase