title: Mass spectrometric analysis of genetic and post-translational heterogeneity in the lectins Jacalin and Maclura pomifera agglutinin.
abstract: Jacalin and M. pomifera agglutinin are T-antigen specific lectins with alpha 4 beta 4 structures that show far greater micro-heterogeneity than plant lectins from other families, due to multiple genetic isoforms and post-translational processing. Electrospray mass spectrometry and combined liquid chromatography-electrospray mass spectrometry were used to characterize the various forms. For both lectins, the mass data were consistent with previous protein sequencing of the major alpha-chain species of 133 residues and three beta-chain species of 20 or 21 residues. In addition, for jacalin the mass of one minor alpha-chain species was consistent with a second of the four reported gene sequences. However, the glycopeptide alpha-chain form and one beta-chain form did not match any of the genes, suggesting a fifth gene remains to be found. For M. pomifera agglutinin, three more beta-chain forms were found, but all six could arise from only two genes, with additional post-translational proteolysis and post-translational substitution with an unidentified component of 106 Da creating the set of six forms. Only two alpha-chain forms were found also, with no glycosylation.
authors.affiliation: Institute for Biological Sciences, National Research Council of Canada, Ottawa.
authors.forename: N M
authors.initials: NM
authors.lastname: Young
authors.forename: D C
authors.initials: DC
authors.lastname: Watson
authors.forename: P
authors.initials: P
authors.lastname: Thibault
mesh_terms: D000595:Amino Acid Sequence; D000957:Antigens, Viral, Tumor / Q000378:metabolism; D018740:Genetic Heterogeneity; D037102:Lectins / Q000737:chemistry* / Q000235:genetics; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry; D037121:Plant Lectins; D011499:Protein Processing, Post-Translational; D017421:Sequence Analysis
chemical_list: D000957:Antigens, Viral, Tumor; D037102:Lectins; D010455:Peptides; D037121:Plant Lectins; C043696:jacalin; C034551:maclurin