Isolation of a glycosylated form of the chicken eggshell protein ovocleidin and determination of the glycosylation site. Alternative glycosylation/phosphorylation at an N-glycosylation sequon.
Ovocleidin, a major protein of the avian eggshell calcified layer, occurs in the eggshell soluble organic matrix in at least two forms. The major form is a phosphoprotein with two phosphorylated serines (OC-17) which was sequenced recently. A minor form is a glycosylated protein with identical sequence and only one phosphorylated serine (OC-23). The site of glycosylation is Asn(59), the only asparagine in the amino acid sequence contained in the N-glycosylation site consensus sequence, N-A-S. Ser(61), which is part of this site, is phosphorylated in OC-17 but not in OC-23 indicating that the two modifications are mutually exclusive. This is the first example of alternative glycosylation/phosphorylation occurring at an N-glycosylation site.
Mann
K
K
Max-Planck-Institut für Biochemie, Am Klopferspitz 18, D-82152, Martinsried, Germany. mann@biochem.mpg.de
D000818:Animals; D001216:Asparagine / Q000737:chemistry; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D004527:Egg Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D010766:Phosphorylation; D012694:Serine / Q000737:chemistry
D004527:Egg Proteins; C095273:ovocleidin 17; D012694:Serine; D001216:Asparagine