Glycoconjugates: mono-, oligo-, or polysaccharides areattachedtoproteins orlipidsGenerallycomplexheteropolymers,ratherthanrepeating homopolymers, such as glycogen and amyloseThe sugars of glycoproteins and glycolipids are referredas GlycansNo singlepredominantfunctionof protein-and lipid-linkedglycans.Similartoproteins,which servediversefunctionsasenzymes,hormones,transportersand structural elements
Glycoconjugates:#monoD,#oligoD,#or#polysaccharides#are# a?ached#to#proteins#or#lipids# Generally#complex#heteropolymers,#rather#than# repea;ng#homopolymers,#such#as#glycogen#and#amylose# The#sugars#of#glycoproteins#and#glycolipids#are#referred# as#Glycans No$single$predominant$func)on$of$protein:$and$lipid:linked$ glycans.$ Similar$to$proteins,$which$serve$diverse$func)ons$as$enzymes,$ hormones,$transporters$and$structural$elements.$
Physical propertiesProviding structural componentsofglycansCell wallsExtracellularmatrixIntrinsicfunctionsperformed by glycansModifying protein propertiesSolubilityProteinsandlipidsareStabilityscaffoldsDirecting trafficking of glycoconjugatesAffect the intrinsic propertiesIntracellularof proteinsExtracellularExtrinsicfunctionsMediating and modulating cell adhesionresultingfromCell-cell interactionsglycan-lectin interactionsCell-matrix interactionsMediating and modulating signallingIntracellularExtracellularTaylorand DrickamerIntroduction toGlycobiology
Physical$proper)es$$ of$glycans Proteins$and$lipids$are$$ scaffolds$ Affect$the$intrinsic$proper)es$$ of$proteins$
1.2 There are three major classes ofglycoconjugates
1.2 There are three major classes of glycoconjugates
Serumand otherfluidsThose attached to lipidsThose attached to proteinsLuminalcompartmentsthrough N (N-linked)O-linked glycanNucleusCPlasmaMembraneCytoplasmReflectsthehistoricalavailability of serumglycoproteinsExtracellularmatrixLuminal/extraceliularglycansCytopiasmic/nuclearAn integral partof the secretoryglycansProteinmachinery of the cellRLipid
Those attached to lipids Those attached to proteins through N (N-linked) O-linked glycan Reflects the historical availability of serum glycoproteins An integral part of the secretory machinery of the cell
Electron micrographofendothelial cells from a blood capillaryCourtesyofGeorgeE.Palade(NP1974)VascularlumendecoratedwithparticlesofcationizedferritinEssentials of GlycobiologyICBChapter 1, Figure 4Second Edition
Chapter#1,#Figure##4# Electron micrograph of endothelial cells from a blood capillary Essen%als(of(Glycobiology(( Second#Edi;on Courtesy of George E. Palade (NP 1974) decorated with particles of cationized ferritin