Collagen Flashcards
What is the most abundant protein in the body?
Collagen
What type of tissue contains collagen?
Connective tissue
- loose
- dense
What are four examples of dense connective tissues that contain collagen?
Bone
Cartilage
Ligaments
Tendons
What type of cell produces collagen?
Fibroblasts
Which ribosomes produce collagen?
Ribosomes on the ER
What form of collagen is produced by the ribosomes?
Preprocollagen
What happens to preprocollagen in the ER?
Signal peptide is cleaved off to form procollagen
Hydroxylation
Triple helix formation
What exactly in procollagen is hydroxylated in the ER?
Proline and lysine residues are hydroxylated
What is the enzyme responsible for hydroxylation of procollagen in the ER?
Prolyl hydroxylase
What does prolyl hydroxylase require in order to function?
Vit C
Fe2+ ions
What is the importance of hydroxylation of procollagen?
Allows for increased hydrogen bonding between collagen chains in triple helix
increased stability of triple helix
What is the disease caused by decreased stability of collagen triple helix?
Scurvy
What type of triple helix does procollagen form?
Right-handed triple helix
What is each collagen chain in the triple helix called?
Alpha chain
How many collagen alpha chains form the triple helix?
Three duh
What are the types of alpha chains that make up type 1 collagen triple helix?
Alpha-1 x2
Alpha-2
What are the features of the triple helix of collagen?
Non-compressible
Non-extensible/high tensile strength
What is the amino acid sequence of the collagen alpha chains?
Glycine-X-Y
X and Y tend to be proline or hydroxyproline
Why is glycine repeated in the collagen alpha chains?
Only amino acid with small enough side chain to fit in the middle of the triple helix
Where are procollagen triple helices transported to from the ER?
Golgi
What happens to procollagen triple helices in the Golgi?
Packaged into vesicles
vesicles bud off from Golgi
What happens to the vesicles containing procollagen triple helices?
Release their contents into the extracellular space by exocytosis
What happens to procollagen triple helices in the cytoplasm?
N and C terminal peptides cleaved off
to form tropocollagen
What happens to tropocollagen in the extracellular space?
Tropocollagen comes together to form collagen fibrils
then collagen fibres
cross-links formed between them
What is responsible for forming cross-links between tropocollagen molecules?
Lysyl oxidase
What does lysyl oxidase require to function?
Vit B6
Cu2+
Why is tropocollagen formed extracellularly rather than inside the fibroblast?
Collagen fibres forming inside the fibroblast would damage and kill the fibroblast
What type of tertiary structure does collagen have?
Fibrous tertiary structure
