Guessing null mutation - (Mar/26/2007 )
Hello All,
There are lots of mutants available for different model organisms like Drosophila, Mouse, C. elegans etc. I am just curious to know if there is any chance you could guess a null mutation by knowing the deleted part of the gene.
For example, if the deletion deletes the whole conserved motif like some sort of domain then its most likely that the mutation produces null allele but if this deletion is not in this motif part and somewhere else where the sequence is not conserved, how can you guess if its making a null allele?
Many thanks
(P.S. - Please post if I am not very clear..)
OK, a small point of semantics. A null mutation results in no protein being expressed. A deletion mutation does result in protein, but depending on where the deletion is, and depending on what is deleted, the resulting protein may be missing a few residues, a domain, or have a frame shift mutation that makes a nonsense protein (very similar to the null mutant). A null allele is simply the result of a non-functional mutation, not necessarily a null mutation.
As a result, I think it would be very hard to develop an algorithm that will allow one to predict the effect of a deletion, unless a great deal was already known about the pathway the protein was in. And if that much data was already known, wold it make an interesting project?
i get confused
u mean here we have two types of mutation,a non-functional mutation and a null mutation ???
aren't they the same ???
can u please explain ???
thanks
As I understand things, a non-functional mutant can be most of the protein, or even all of it, but non-active (if it's an enzyme, say), but a null mutant doesn't make anything. You're right, it is a subtle difference.
Definition of Null mutation
Null mutation: A mutation (a change) in a gene that leads to its not being transcribed into RNA and/or translated into a functional protein product.
For example, a null mutation in a gene that usually encodes a specific enzyme leads to the production of a nonfunctional enzyme or no enzyme at all.
taken from Medicine Net.com
it seems that non-functional mutation is included in null mutation...
isn't it ??
Null mutation: A mutation (a change) in a gene that leads to its not being transcribed into RNA and/or translated into a functional protein product.
For example, a null mutation in a gene that usually encodes a specific enzyme leads to the production of a nonfunctional enzyme or no enzyme at all.
taken from Medicine Net.com
it seems that non-functional mutation is included in null mutation...
isn't it ??
Perhaps what also matters is the perspective you're taking. It seems that the difference of definitions may be partly caused by the field of science considered. A protein chemist may consider a non-functioning mutation as simply a mutation, and only a mutation that totally destroys expression as being a null mutation, whereas a cell biologist might consider any change that stops the phenotype being seen is a null mutation.
thanks
and sorry Jiang M,i have got away from the major topic you
are discussing ....