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

FEBS Letters

Fiorilli, Amelia¹  Gravaghi, Claudia¹  Tettamanti, Guido¹  Ferraretto, Anita¹ 

[1] Department of Medical Chemistry, Biochemistry and Biotechnology, The Medical Faculty, University of Milan, L.I.T.A., Via Fratelli Cervi 93, 20090 Segrate, Milan, Italy

关键词: Casein phosphopeptide;    Fura-2;    HT-29 cell;    Calcium imaging;    [Ca2+]i;    intracellular free calcium concentration;    CPP;    casein phosphopeptide;    CN;    casein;    β-CN(1–25)4P;    a CPP constituted by the 1–25 N-terminal fragment from β-casein carrying four residues of phosphorylated serine;    αs1-CN(59–79)5P;    a CPP constituted by the 59–79 fragment from αs1-casein;    carrying five residues of phosphorylated serine;    KRH;    Krebs–Ringer–HEPES;   

DOI  :  10.1016/S0014-5793(03)00741-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Casein phosphopeptides β-CN(1–25)4P and α_s1-CN(59–79)5P, from β- and α_s1-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 Ca²⁺. The response was quantitatively higher with β-CN(1–25)4P than α_s1-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.

【 授权许可】

Unknown