Biochemical and Biophysical Research Communications, Vol.410, No.3, 632-636, 2011
Effects of length and amino acid sequence of O-mannosyl peptides on substrate specificity of protein O-linked mannose beta 1,2-N-acetylglucosaminyltransferase 1 (POMGnT1)
Protein O-linked mannose beta 1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) catalyzes the transfer of G1cNAc to O-mannose of glycoproteins. Mutations in the POMGnT1 gene cause muscle-eye-brain disease (MEB). POMGnT1 is a typical type 11 membrane protein, which is localized in the Golgi apparatus. However, details of the catalytic and reaction mechanism of POMGnT1 are not understood. To develop a better understanding of POMGnT1, we examined the substrate specificity of POMGnT1 using a series of synthetic O-mannosyl peptides based on the human alpha-dystroglycan (alpha-DG) sequence as substrates. O-Mannosyl peptides consisting of three to 20 amino acids are recognized as substrates. Enzyme kinetics improved with increasing peptide length up to a length of 8 amino acids but the kinetics of peptides longer than 8 amino acids were similar to those of octapeptides. Our results also show that the amino acid sequence affects POMGnT1 activity. These data suggest that both length and amino acid sequence of mannosyl peptides are determinants of POMGnT1 substrate specificity. (C) 2011 Elsevier Inc. All rights reserved.