Biosynthesis and oligosaccharide processing of human Tamm-Horsfall glycoprotein permanently expressed in HeLa cells.
Human Tamm-Horsfall glycoprotein (T-H) is produced by renal cells of ascending limb of loop of Henle and is largely excreted in urine. N-linked glycans account for close to 30% of the weight of T-H. We studied the biosynthesis of recombinant T-H permanently expressed in HeLa cells. The conversion from the precursor (84 kDa) to the mature form (97 kDa) mainly depends on the processing of glycans from the high-mannose to polyantennary type. The conversion from precursor to mature form is very slow and the glycan structure of precursor appears to be that of a glycoprotein not yet processed by Golgi alpha 1,2 mannosidase. Since T-H has a very high number of disulfide bridges (more than 50 cysteine residues/mol) one may infer that the rate limiting step for the precursor export out of ER is the formation of a correct set of disulfide bonds. Mature T-H isolated from HeLa cells retained one N-linked chain with the high-mannose structure similarly to urinary T-H. This result indicates that the occurrence of one unprocessed high-mannose chain in mature T-H is host-cell independent and very likely related to the T-H primary structure.
Serafini-Cessi
F
F
Department of Experimental Pathology, University of Bologna, Italy.
Malagolini
N
N
Hoops
T C
TC
Rindler
M J
MJ
D002240:Carbohydrate Sequence; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D003001:Cloning, Molecular; D006020:Glycopeptides / Q000302:isolation & purification; D006031:Glycosylation; D006367:HeLa Cells; D006801:Humans; D008358:Mannose / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000096:biosynthesis* / Q000652:urine; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000096:biosynthesis; D014162:Transfection; D058949:Uromodulin
D006020:Glycopeptides; D009088:Mucoproteins; D009844:Oligosaccharides; D011994:Recombinant Proteins; C548612:UMOD protein, human; D058949:Uromodulin; D008715:Methionine; D008358:Mannose