Human TPST1 transmembrane domain triggers enzyme dimerisation and localisation to the Golgi compartment
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Colleges, School and Institutes
TPST1 is a human tyrosylprotein sulfotransferase that uses 3'phosphoadenosine-5'phosphosulfate (PAPS) to transfer the sulfate moiety to proteins predominantly designated for secretion. To achieve a general understanding of the cellular role of human tyrosine-directed sulfotransferases, we investigated targeting, structure and posttranslational modification of TPST1. Golgi localisation of the enzyme in COS-7 and HeLa cells was visualised by fluorescence imaging techniques. PNGase treatment and mutational studies determined that TPST1 bears N-linked glycosyl residues exclusively at position Asn60 and Asn262. By alanine mutation of these asparagine residues, we could determine that the N-linked oligosaccharides do not have an influence on Golgi retention of TPST1. In concert with N and C-terminal flanking residues, the transmembrane domain of TPST1 was determined to act in targeting and retention of the enzyme to the trans-Golgi compartment. This domain exhibits a pronounced secondary structure in a lipid environment. Further in vivo FRET studies using the transmembrane domain suggest that the human tyrosylprotein sulfotransferase may be functional as homodimer/oligomer in the trans-Golgi compartment.
|Number of pages||14|
|Journal||Journal of Molecular Biology|
|Publication status||Published - 18 Aug 2006|
- Amino Acid Sequence, Animals, Asparagine, Autoantigens, COS Cells, Cercopithecus aethiops, Dimerization, Fluorescence Resonance Energy Transfer, Glycosylation, Golgi Apparatus, HeLa Cells, Humans, Intracellular Membranes, Molecular Sequence Data, Mutation, Oligosaccharides, Protein Binding, Protein Processing, Post-Translational, Protein Structure, Tertiary, Sulfotransferases