Casein-derived bioactive phosphopeptides: Role of phosphorylation and primary structure in promoting calcium uptake by HT-29 tumor cells

Anita Ferraretto, Claudia Gravaghi, Amelia Fiorilli, Guido Tettamanti

Research output: Contribution to journalArticlepeer-review

Abstract

Casein phosphopeptides β-CN(1-25)4P and α s1-CN(59-79)5P, from β- and αs1-casein, respectively, both carrying the characteristic 'acidic motif' Ser(P)-Ser(P)-Ser(P)-Glu-Glu, were chemically synthesized and administered to HT-29 cells differentiated in culture, which are a used model of intestinal epithelium for absorption studies. Both casein phosphopeptides caused an increase of [Ca2+]i due to influx of extracellular Ca 2+. The response was quantitatively higher with β-CN(1-25)4P than αs1-CN(59-79)5P. The synthetic peptide corresponding to the 'acidic motif' was ineffective and the dephosphorylated form of β-CN(1-25)4P almost inactive. The lack of the N-terminally located five amino acids, or sequence modifications within the N-terminal segment of β-CN(1-25)4P, caused a total loss of activity, whereas the lack of the C-terminal segment preserved activity. In conclusion, the influx of calcium into HT-29 cells caused by β-CN(1-25)4P appears to depend on the phosphorylated 'acidic motif' and the preceding N-terminal region.

Original languageEnglish
Pages (from-to)92-98
Number of pages7
JournalFEBS Letters
Volume551
Issue number1-3
DOIs
Publication statusPublished - Sep 11 2003

Keywords

  • Calcium imaging
  • Casein phosphopeptide
  • Fura-2
  • HT-29 cell

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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