title: The cysteine proteinase inhibitor chicken cystatin is a phosphoprotein.
abstract: Peptide maps obtained by reversed-phase HPLC of tryptic digests of isoelectric form 1 (pI = 6.5) and 2 (pI = 5.6) of chicken egg white cystatin revealed that the difference was located only in a single peptide (residues Ser-74-Lys-91). Ser-80 of cystatin 2 was subsequently identified as being modified by phosphorylation. Moreover, alkaline phosphatase treatment of a mixture of native cystatin forms 1 and 2 was shown by ion-exchange chromatography to cause the disappearance of isoelectric form 2 with a concomitant increase in form 1. Thus, the existence of two isoelectric forms of chicken cystatin is due to the phosphorylated form 2 and non-phosphorylated form 1.
authors.affiliation: Max-Planck-Institut für Biochemie, Martinsried, FRG.
authors.forename: B
authors.initials: B
authors.lastname: Laber
authors.forename: K
authors.initials: K
authors.lastname: Krieglstein
authors.forename: A
authors.initials: A
authors.lastname: Henschen
authors.forename: J
authors.initials: J
authors.lastname: Kos
authors.forename: V
authors.initials: V
authors.lastname: Turk
authors.forename: R
authors.initials: R
authors.lastname: Huber
authors.forename: W
authors.initials: W
authors.lastname: Bode
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D006868:Hydrolysis; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000032:analysis*; D011506:Proteins / Q000032:analysis*; D014357:Trypsin
chemical_list: D000596:Amino Acids; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D010750:Phosphoproteins; D011506:Proteins; C100158:cystatin, egg-white; D014357:Trypsin