Question

Proteins with low complexity domains (LCD’s) are known to be important in the formation of amyloid fibrils?   Why?   Clue: LCDs are intrinsically unstructured and made of neutral, non polar, hydrophobic amino acids.   Why is all this important in formation of amyloid fibrils?

Answer 1

ANS. Amyloid is a kind of insoluble protein which tends to deposits extracellular and intracellular in the tissues.They exist in the form of fibrils .As the low complexity domains proteins are  intrinsically unstructured and made up of neutal ,non polar,hydrophobic amino acid so it resultts in the easily fomation of beta pleated sheet conformation that is a secondary structure.More than 20 types of amino acids have been identified which have facility of formation of beta pleated sheets conformation and hence also for amyloid fibrils.The formation of amyloid initates with misfold protein resulting in amyloid seed then amyloid filament and finally amyloid fibril which is thick in size.Amyloid fibril can cause compression of normal tissue and replacement of normal functional tissue with amyloid that is insoluble and abnormal protein