TY - JOUR
T1 - UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase. Identification and separation of two distinct transferase activities.
AU - Sørensen, T
AU - White, T
AU - Wandall, H H
AU - Kristensen, A K
AU - Roepstorff, P
AU - Clausen, H
N1 - Keywords: Amino Acid Sequence; Animals; Chromatography, Affinity; Chromatography, Gel; Chromatography, Ion Exchange; Female; Humans; Isoenzymes; Kinetics; Liver; Molecular Sequence Data; N-Acetylgalactosaminyltransferases; Organ Specificity; Peptides; Placenta; Pregnancy; Rats; Sheep; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Submandibular Gland; Substrate Specificity; Swine
PY - 1995
Y1 - 1995
N2 - Using a defined acceptor substrate peptide as an affinity chromatography ligand we have developed a purification scheme for a unique human polypeptide, UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (GalNAc-transferase) (White, T., Bennett, E.P., Takio, K., Sørensen, T., Bonding, N., and Clausen, H. (1995) J. Biol. Chem. 270, 24156-24165). Here we report detailed studies of the acceptor substrate specificity of GalNAc-transferase purified by this scheme as well as the Gal-NAc-transferase activity, which, upon repeated affinity chromatography, evaded purification by this affinity ligand. Using a panel of acceptor peptides, a qualitative difference in specificity between these separated transferase activities in four rat organs and two human organs also revealed qualitative differences in specificity. The results support the existence of multiple Gal-NAc-transferase activities and suggest that these are differentially expressed in different organs. As the number of GalNAc-transferases existing is unknown, as is the specificity of the until now cloned and expressed GalNAc-transferases (T1 and T2), it is as yet impossible to relate the results obtained to specific enzyme proteins. The identification of acceptor peptides that can be used to discriminate GalNAc-transferase activities is an important step toward understanding the molecular basis of GalNAc O-linked glycosylation in cells and organs and in pathological conditions.
AB - Using a defined acceptor substrate peptide as an affinity chromatography ligand we have developed a purification scheme for a unique human polypeptide, UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (GalNAc-transferase) (White, T., Bennett, E.P., Takio, K., Sørensen, T., Bonding, N., and Clausen, H. (1995) J. Biol. Chem. 270, 24156-24165). Here we report detailed studies of the acceptor substrate specificity of GalNAc-transferase purified by this scheme as well as the Gal-NAc-transferase activity, which, upon repeated affinity chromatography, evaded purification by this affinity ligand. Using a panel of acceptor peptides, a qualitative difference in specificity between these separated transferase activities in four rat organs and two human organs also revealed qualitative differences in specificity. The results support the existence of multiple Gal-NAc-transferase activities and suggest that these are differentially expressed in different organs. As the number of GalNAc-transferases existing is unknown, as is the specificity of the until now cloned and expressed GalNAc-transferases (T1 and T2), it is as yet impossible to relate the results obtained to specific enzyme proteins. The identification of acceptor peptides that can be used to discriminate GalNAc-transferase activities is an important step toward understanding the molecular basis of GalNAc O-linked glycosylation in cells and organs and in pathological conditions.
M3 - Journal article
C2 - 7592620
SN - 0021-9258
VL - 270
SP - 24166
EP - 24173
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 41
ER -