I have noticed that several microtubule-associated proteins contain stretches of glutamine residues. Is there a particular reason for the presence of such Q-rich regions?
Ok
1. Glutamin can produce a site for attachment of glutamine binding proteins. This interaction induce more stability in the proteins (Proteins. 2005; 58(1):80-87).
2. Glutamine is a polar aminoacid and can participate in hydrogene bonds formation. Such bonds are very important in the 2nd, 3rd and 4th level of protein structure.
Changes of glutaminyl residues into glutamyl residues would be expected to have a profound effect on the conformation of the protein, resulting in its polymerization.
Changes of glutamine for glutamic acid could also produce the differences on its silver staining properties
For example in Alzheimer disease, microtubule associated protein tau factor self-assembles into filamentous structures resembling the paired helical filamentsin this AD. Tau polymerization requires of a previous modification; conversion of glutamine into glutamic acid by deamination.
On the other hand, it has been proposed that deamination may play a general role in the ageing of living organisms.
Please use the following article for better understanding:
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, Vol. 141, No. 2, 1986: 790-796
Yes that is quite true in case of the pathological condition. However, during normal functioning of the tau protein or other MAPs, what is the role of Q-rich stretches? Does this conversion occur during non-pathological conditions?
Ok
1. Glutamin can produce a site for attachment of glutamine binding proteins. This interaction induce more stability in the proteins (Proteins. 2005; 58(1):80-87).
2. Glutamine is a polar aminoacid and can participate in hydrogene bonds formation. Such bonds are very important in the 2nd, 3rd and 4th level of protein structure.
Maybe this reference, although old helps, on the issue
Hughes and Olson "Therapeutic opportunities in polyglutamine disease" NATURE MEDICINE • VOLUME 7 • NUMBER 4 • APRIL 2001
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