QUESTION 13 1 po Extracellular proteins like collagens, integrins, and laminins

Question

QUESTION 13 1 po Extracellular proteins like collagens, integrins, and laminins form large complexes stabilized by chemical modifications to specific amino acids on individual peptides, ie they are often cross linked to provide a larger more concrete structure Based upon this, what sorts of modifications might be present on the EGF repeats of integrins and lamins? Pick ALL that apply A glycoslation (addition of sugars) B hydroxylation (addition of hydroxyl groups) C hydrophobic interactions disulfide bridges E none of these are likely QUESTION 14

Explanation / Answer

Extracellular proteins forms large complexes stabilized by chemical modificatins of internal amino acid residues.

Such modifications are -

A. Glycosylation ( addition of sugar )

B. Hydroxylation ( addition of hydroxyl groups )

D. Disulfide bond formation

All these 3 modifications comes under one roof of Post-translational modifications of Extracellular matix proteins.

The repeating structure, represented as (Gly-X-Y)n, is an absolute requirement for the formation of the triple helix in collagen. While X and Y can be any other amino acids, about 100 of the X positions are proline and about 100 of the Y positions are hydroxyproline. Proline and hydroxyproline confer rigidity on the collagen molecule. Hydroxyproline is formed by the posttranslational hydroxylation of peptide-bound proline residues catalyzed by the enzyme prolyl hydroxylase, whose cofactors are ascorbic acid (vitamin C) and -ketoglutarate. Lysines in the Y position may also be posttranslationally modified to hydroxylysine through the
action of lysyl hydroxylase, an enzyme with similar cofactors. Some of these hydroxylysines may be further modified by the addition of galactose or galactosyl-glucose through an O-glycosidic linkage, a glycosylation site that is unique to collagen.

And again there is  intrachain disulfide bonds between the N- and C-terminal propeptide sequences to align the three chains before the triple helix formation of collagen fibers in Extracellular matrix.

Thanks for asking.

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.