Lecture 14 Carbohydrate recognitionin cell adhesion and signalling
Lecture'14'Carbohydrate'recogni4on' in'cell'adhesion'and'signalling
Learning objects. The classification of sugar-binding proteins basedon structures of carbohydrate-recognitiondomains The roles of mannose-binding protein and otherC-type lectins in innate immunity· How the selectins function as cell-adhesionmolecules The adhesion and signalling functions of siglecs intheimmunesystem: How galectins modulate adhesion and signallingin lymphocytes（淋巴细胞)and other cells
Learning'objects' • The'classifica4on'of'sugar;binding'proteins'based' on'structures'of'carbohydrate;recogni4on' domains' • The'roles'of'mannose;binding'protein'and'other' C;type'lec4ns in'innate'immunity' • How'the'selec4ns'func4on'as'cell;adhesion' molecules' • The'adhesion'and'signalling'func4ons'of'siglecs in' the'immune'system' • How'galec4ns modulate'adhesion'and'signalling in'lymphocytes'(淋巴细胞)'and'other'cells
Lectins serve asreceptorsforspecificglycansrecognizeforeigncell surfaces mediate or modulate immune responses topathogens: bind to endogenous carbohydrates: mediate adhesion or signalling events at thecellsurface
• Lec4ns serve'as'receptors'for'specific'glycans'' • recognize'foreign'cell'surfaces'' • mediate'or'modulate'immune'responses'to' pathogens'' • bind'to'endogenous'carbohydrates'' • mediate'adhesion'or'signalling'events'at'the' cell'surface
1 Animal lectins can be classifiedaccording to their structures
1 Animal lectins can be classified according to their structures
Carbohydrate-recognitiondomains(CRD)· CRDs are responsible for the recognition functionsof the lectins. Other domains in the lectins mediate subseguentresponses· Different types of CRD have distinct ancestry (家谱)and different polypeptide foldsThe overall folds of CRDs are determined byconserved residues that are characteristic of eachfamilyofCRDsThese residues form the hydrophobic core and insome cases disulphide bonds and binding sitesfordivalent cations
• CRDs'are'responsible'for'the'recogni4on'func4ons' of'the'lec4ns • Other'domains'in'the'lec4ns'mediate'subsequent' responses'' • Different'types'of'CRD'have'dis4nct'ancestry'(家谱)' and'different'polypep4de'folds' • The'overall'folds'of'CRDs'are'determined'by' conserved'residues'that'are'characteris4c'of'each' family'of'CRDs' • These'residues'form'the'hydrophobic'core'and'in' some'cases'disulphide'bonds'and'binding'sites'for' divalent'ca4ons Carbohydrate-recognition domains (CRD)