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34 Cards in this Set

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What are the constituents of the extracellular matrix?
1. Collagen
2. Glycoprotein
3. Proteoglycan
What are the modular building blocks of connective tissue?
1. Collagen
2. Glycoproteins
3. Proteoglycans
ECM is basically a composite material of what two element?
1. Semi-rigid linear elements (e.g.-collagens)
2. Flexible, space-filling elements (e.g.-glycoproteins and proteoglycans)
What are the two "themes" in ECM?
1. Interstitial Connective Tissue
2. Basement membrane
What is the composite of polyproteins found in basement membranes?
1. Fibrillar proteins
2. Glycoproteins
3. Proteoglycans
What are the two layers that make up the basement membrane?
1. Basal Lamina
2. Reticular Lamina
What are the two layers of basal lamina?
Lamina Rara (top layer)
Lamina Densa (bottom layer)
What are the components of intertitial connective tissue?
1. Fibrillar component
2. Glycoproteins
3. Proteoglycans
What is the general structure of collagen?
Three polypeptide chains (alpha chains) which are wrapped around one another to form a LEFT handed triple helix.
What is the seqeunce found in the polypeptide chain of collagen?
Gly-X-Y (where X is usually a proline and Y is usually a hyrdoxyproline)
What happens when proline is in the Y position of the Gly-X-Y triplet?
Prolyl hydroxylase will come in and convert it to 4-hydroxyproline.
What happens when lysine is in the Y position of the Gly-X-Y triplet?
Lysyl hydroxylase will convert it to hydroxylysine
How would you read α1[I]?
Alpha chain, number 1, from the Type I collagen family.
How would you read [α1(I)]1 [α2(II)]2?
A Type I trimer of 2 alpha 1 chains, and 1 alpha 2 chain.
What occurs on the α chains have translation?
Immediate posttranslational modification.
Give an example of posttranslational modification in collagen synthesis.
Prolines become modified to hydroxyprolines (by prolyl hydroxylase) or lysines become modified to become hydroxylysines (by lysyl hydroxylase)
Is there any further modifications seen after immediate posttranslational modification?
Yes. Hydroxylysine residues are further modified via glycosylation.
Describe`
Answers
What is this and describe its structure.
This is a fibril forming collagen. In "native" fibrils, the collagen molecules have repeat structures of 1 "hole zone" and 1 "overlap" zone with 1/4 staggared conformation.
The fibrous backbone of ECM is also known as?
Collagen
Describe the organization of interstitial ECM in comparison to basement membrane ECM.
Similar in organization
Glycosylation of alpha chains occurs when?
When you have hydroxylysine
Which end does the assembly of collagen begin?
At the carboxy end. Then proceeds to the amine end in zipper like fashion.
The information needed for processing and assembly of collagen is located where?
Inherent in the collagen structure.
Where does procesing occur for collagen?
Outside of cell.
Within collagen, what is the enzyme responsible for INTRA-molecular crosslinks and where do they crosslink?
Lysl-oxidase.

Crosslinks at between hydroxylysines.
What type of modification is VERY important in collagen structure?
Post-translational modification.
Structure of FACIT collagens allow for what?
Globular domains allow for stability.
Type IV collagens are used for what structures?
Basement membrane.
Describe the structure of Type IV collagens.
Globular domains dimerize head to head on the carboxy terminus. These dimers then form a tetramer in the 7s region at the amino terminus. Leads to big network.
How do you decrease the melting temperature Point of collagen?
Decrease the number of hydroxyproline
What are the cofactors required in collagen post-translational modification.
Ascorbic acid and Iron
How is Osteogenesis Imperfecta associated with collagen formation?
A mutation leads to a frameshift leading to the loss of a cysteine in the carboxy end (meaning assembly is tough) causing non-incorporation to a trimer.
Give two examples of post-secretory modification in collagen synthesis.
1. Cleavage of N and C terminus propeptides.
2. Covalent cross-linking