PMID: 16859706

 

    Legend: Sugar

Title : Human TPST1 transmembrane domain triggers enzyme dimerisation and localisation to the Golgi compartment

Abstract :

1. TPST1 is a human tyrosylprotein sulfotransferase that uses 3'phosphoadenosine-5'phosphosulfate (PAPS) to transfer the sulfate moiety to proteins predominantly designated for secretion
2. To achieve a general understanding of the cellular role of human tyrosine-directed sulfotransferases, we investigated targeting, structure and posttranslational modification of TPST1
3. Golgi localisation of the enzyme in COS-7 and HeLa cells was visualised by fluorescence imaging techniques
4. PNGase treatment and mutational studies determined that TPST1 bears N-linked glycosyl residues exclusively at position Asn60 and Asn262
5. 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
6. 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
7. This domain exhibits a pronounced secondary structure in a lipid environment
8. 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