C-mannosylation and o-fucosylation of thrombospondin type 1 repeats.
The final chemical structure of a newly synthesized protein is often only attained after further covalent modification. Ideally, a comprehensive proteome analysis includes this aspect, a task that is complicated by our incomplete knowledge of the range of possible modifications and often by the lack of suitable analysis methods. Here we present two recently discovered, unusual forms of protein glycosylation, i.e. C-mannosylation and O-fucosylation. Their analysis by a combined mass spectrometric approach is illustrated with peptides from the thrombospondin type 1 repeats (TSRs) of the recombinant axonal guidance protein F-spondin. Nano-electrospray ionization tandem-mass spectrometry of isolated peptides showed that eight of ten Trp residues in the TSRs of F-spondin are C-mannosylated. O-Fucosylation sites were determined by a recently established nano-electrospray ionization quadrupole time-of-flight tandem-mass spectrometry approach. Four of five TSRs carry the disaccharide Hex-dHex-O-Ser/Thr in close proximity to the C-mannosylation sites. In analogy to thrombospondin-1, we assume this to be Glc-Fuc-O-Ser/Thr. Our current knowledge of these glycosylations will be discussed.
Gonzalez de Peredo
Anne
A
Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.
Klein
Dominique
D
Macek
Boris
B
Hess
Daniel
D
Peter-Katalinic
Jasna
J
Hofsteenge
Jan
J
D020816:Amino Acid Motifs; D016326:Extracellular Matrix Proteins; D005643:Fucose / Q000378:metabolism*; D006020:Glycopeptides / Q000737:chemistry*; D006031:Glycosylation; D006133:Growth Substances; D006801:Humans; D008358:Mannose / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods*; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism*; D010455:Peptides; D011499:Protein Processing, Post-Translational; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D019700:Thrombospondin 1 / Q000737:chemistry / Q000378:metabolism*
D016326:Extracellular Matrix Proteins; D006020:Glycopeptides; D006133:Growth Substances; D019006:Neural Cell Adhesion Molecules; D010455:Peptides; D011993:Recombinant Fusion Proteins; C429104:SPON1 protein, human; D019700:Thrombospondin 1; D005643:Fucose; D008358:Mannose