amylose amylopectin or glycogen glycogen and amylopectin structures glycogen and amylopectin are ...
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Glycogen and Amylopectin Structures
Glycogen andAmylopectin are(1-4) chains withwith (1-6)branches
Amylopectin Glycogen
Pol
ysac
char
ides
Carbohydrates – Complex (Polysaccharides)
Cellulose = polysaccharide found in plant cell walls
Cellulose fibers
Macrofibril
Microfibril
Chains of cellulose
Glycoprotein
• Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide side-chains.
• The process of attaching the glycans is known as glycosalation.
• The sugar groups attached to glycoprotein can assist in protein folding or improve a proteins’ stability.
Functions of Glycoproteins
Function Glycoprotein
Structural Molecule Collagen
Lubricant and Protective Agent Mucins
Transport Molecule Transferrin, ceruloplasmin
Immunologic Molecule Immunoglobins, histocompatibility antigens
Enzyme Various, e.g alkaline phosphatase
Cell Attachment-recognition site Proteins involved in cell to cellc ommunication
Interact with specific carbohydrates Lectins, selectins (cell adhesion lectins), antibodies
Functions of Glycoproteins
Function Glycoprotein
Receptor Various Proteins in hormone and drug action
Affect folding of certain proteins Calnexin, Calreticulin
Regulation of development Notch and its analogs, key proteins in development
Hemostasis (and thrombosis) Specific glycoproteins on the surface membranes of platelets
glycosaminoglycans of extracellular matrix
lubricants in the synovial fluid of joints
cartilage, tendons, ligaments
a variety of horny structures formed of dead cells: horn, hair, hoofs, nails
A typical tetrasaccharide linker (blue) connects a glycosamino-glycan—in this case chondroitin 4-sulfate (orange)—to a Ser residue (pink) in the core protein. The xylose residue at the reducing end of the linker is joined by its anomeric carbon to the hydroxyl of the Ser residue.
Proteoglycans: cell surface or extracellular matrix
One very long molecule of hyaluronan is associated noncovalently with about 100 molecules of the core protein aggrecan
Proteoglycan aggregate of the extracellular matrix
Interactions between cells and the extracellular matrix
with binding sites for both integrin and the proteoglycan
Lectins, found in all organisms, are proteins that bind carbohydrates with high specificity
cell-cell recognition, signaling, adhesion processes, intracellular targeting, deterrent to insects
lectin-ligand interactions in lymphocyte movement to the site of an infection
Stronger interaction nearthe site of inflammation
Helicobacter pylori
Interaction between a bacterial surface lectin and an oligosaccharide of the gastric epithelium
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