Question

Which of the following issues will not cause a direct defect in collagen synthesis/trafficking?

A) deficiency in vitamin C

B) deficiency in mannose-6-phosphate

C) deficiency in procollagen-N-propeptidase

D) deficiency in lysyl oxidase

Answer 1

Answer-

According to the given question-

Collagen synthesis-  Collagen are proteins made up of several amino acids present in ligaments,bones, skin and tendons and provide support to connective tissues. Collagen is made up of three  chains wounded together to form triple helix. the synthesis of collagen takes place in fibroblasts cells . collagen synthesis pathway is highly regulated but some times the mutations in gene , deficiency of nutritional component , posttranslational modification responsible for causing effect in collagen synthesis.

• Deficiency of Vitamin C or ascorbic acid causes changes in the activity and function of hydroxylase enzyme in collagen synthesis.
• deficiency in mannose-6-phosphate- are responsible for causing Inclusion-cell or I-cell disease. in this disease the defect in enzyme  phosphotransferase occur which transfer phosphate to mannose molecule that are responsible for protein targeting inside the cell.
• Deficiency in procollagen-N-propeptidase - this enzymes belongs to protease family and responsible for removing the  the terminal peptides present in the  procollagen. the deficiency of this enzyme leads to a disaorder in collagen called dermatosparaxis or Ehlers–Danlos syndrome.

• Deficiency in lysyl oxidase-  Lysyl oxidase is a enzyme that required copper as cofactor for their catalytic activity and this enzymes catalyses lysine and hydroxylysines amino acid and also acts on covalent bonding between tropocollagen molecules that are responsible for forming a collagen fibril molecule.

So based on the above information the  collagen synthesis/trafficking are not affected by B) deficiency in mannose-6-phosphate