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Title
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The cysteine proteinase inhibitor chicken cystatin is a phosphoprotein.
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Authors
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B.Laber,
K.Krieglstein,
A.Henschen,
J.Kos,
V.Turk,
R.Huber,
W.Bode.
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Ref.
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Febs Lett, 1989,
248,
162-168.
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PubMed id
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Abstract
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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.
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