Rabbit urinary tamm-horsfall glycoprotein. Chemical composition and tentative carbohydrate structure.
The urinary Tamm-Horsfall protein (THP) is the major glycoprotein secreted by the mammalian kidney. We recently isolated and immortalized thick ascending limb of Henle cells from rabbit kidney, which produce Tamm-Horsfall protein in cell culture in vitro. In order to further study the yet undefined functional role and biosynthetic pathways of this protein, we first re-examined the chemical composition and the carbohydrate structure of rabbit urinary Tamm-Horsfall protein. Using precipitation with 0.58 mol/l NaCl a protein was isolated from rabbit urine which showed extensive microheterogeneity and had an average molecular mass of 95 kDa. Deglycosylation of the protein led to a loss of microheterogeneity and yielded a molecular mass of 58-60 kDa. Amino-acid analysis of the native and deglycosylated protein revealed a lower cysteine (20 mol/mol THP) and a higher histidine (20 mol/mol THP) content than described previously. Chemical analysis of the carbohydrates showed a high glucosamine (50 mol/mol THP), galactose (43 mol/mol THP), and mannose (24 mol/mol THP) content. The amount of sialic acid was 15 mol/mol THP. Using lectins to identify the structure of the carbohydrate chains it was shown that rabbit Tamm-Horsfall protein possesses complex-type oligosaccharide chains with terminal sialic acid, beta-galactose, and probably alpha-fucose and chains of the mucin type. These results indicate that some of the cysteine residues in the polypeptide chain of THP can be replaced by histidine, suggesting a role of some cysteins in metal binding rather than intramolecular stabilization.(ABSTRACT TRUNCATED AT 250 WORDS)
Fabricius
T
T
Max-Planck-Institut für Systemphysiologie, Dortmund.
Scott
D M
DM
Kinne
R K
RK
D000596:Amino Acids / Q000032:analysis; D000606:Amino Sugars / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005643:Fucose / Q000032:analysis; D006639:Histidine / Q000032:analysis; D006801:Humans; D037102:Lectins / Q000032:analysis; D008297:Male; D009088:Mucoproteins / Q000652:urine*; D010783:Photometry; D011817:Rabbits; D012794:Sialic Acids / Q000032:analysis; D013045:Species Specificity; D058949:Uromodulin
D000596:Amino Acids; D000606:Amino Sugars; D002241:Carbohydrates; D037102:Lectins; D009088:Mucoproteins; D012794:Sialic Acids; C548612:UMOD protein, human; D058949:Uromodulin; D005643:Fucose; D006639:Histidine