FEBS Letters | |
Isolation and characterization of circulating 13‐kDa C‐terminal fragments of human insulin‐like growth factor binding protein‐5 | |
Wobst, Philip1  Forssmann, Wolf-Georg1  Mark, Silke1  Ständker, Ludger1  | |
[1]Lower Saxony Institute for Peptide Research (IPF), Feodor-Lynen Str. 31, D-30625 Hannover, Germany | |
关键词: Insulin-like growth factor-binding protein-5; Hemofiltrate; Plasma proteolysis; Glycosylation; ESI-MS; electrospray mass spectrometry; HF; hemofiltrate; MALDI-MS; matrix assisted laser desorption ionization mass spectrometry; IGF; insulin-like growth factor; IGFBP; insulin-like growth factor binding protein; | |
DOI : 10.1016/S0014-5793(98)01497-5 | |
学科分类:生物化学/生物物理 | |
来源: John Wiley & Sons Ltd. | |
【 摘 要 】
The insulin-like growth factor binding proteins (IGFBPs) are responsible for regulation of the effects and the bioavailability of the insulin-like growth factors (IGFs). We screened for circulating fragments of human IGFBP-5 in human hemofiltrate. Identification of IGFBP-5 peptides in the fractions of our peptide bank generated from hemofiltrate was performed by their immunoreactivity and their capacity to bind IGF-I. Different fragments of IGFBP-5 with molecular sizes from 12 to 25 kDa were identified. C-terminal peptides of IGFBP-5 with molecular masses of 13.3 and 13.5 kDa were purified by consecutive chromatographic steps and sequenced. Sequence analysis of the peptides revealed the (double) sequences (K)FVGGAENXAHPRII and MVPRAVYLPNXDRKG. In addition, a smaller fragment with M r 2722 of the central IGFBP-5 region was purified and showed the sequence HTRISELKAEAVKKDRRKKLTQS (residues 121–143) indicating plasma proteolysis of IGFBP-5 C-terminal to amino acids Lys-120, Ser-143, Lys-144, and Arg-188. According to mass spectrometric and sequence analysis, Thr-152 was shown to be O-glycosylated. Fractions containing C-terminal IGFBP-5 fragments revealed significant IGF-I binding properties. Our results indicate that plasma proteolysis of IGFBP-5 preferentially occurs C-terminally to basic residues and generates different C-terminal fragments, possibly acting in an IGF-dependent manner and bearing intrinsic biological functions.
【 授权许可】
Unknown
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