Analysis of human C1q by combined bottom-up and top-down mass spectrometry: detailed mapping of post-translational modifications and insights into the C1r/C1s binding sites.

ABSTRACT: C1q is a subunit of the C1 complex, a key player in innate immunity that triggers activation of the classical complement pathway. Featuring a unique structural organization and comprising a collagen-like domain with a high level of post-translational modifications, C1q represents a challenging protein assembly for structural biology. We report for the first time a comprehensive proteomics study of C1q combining bottom-up and top-down analyses. C1q was submitted to proteolytic digestion by a combination of collagenase and trypsin for bottom-up analyses. In addition to classical LC-MS/MS analyses, which provided reliable identification of hydroxylated proline and lysine residues, sugar loss-triggered MS(3) scans were acquired on an LTQ-Orbitrap (Linear Quadrupole Ion Trap-Orbitrap) instrumen

SUBMITTER: Pflieger D 

PROVIDER: S-EPMC2860232 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature