Role of snRNA in telomeric maintenance?

[Helix]

I was researching rRNA and tRNA when I stumbled an other kind of RNA: snRNA. It appears snRNA's have a role in maintaining telomeres, the terminal repeats at the ends of our chromosomes.

 

Can anyone tell me more about snRNA. I am doing a research project on telomeres and knowing the presice function of snRNA would be good. Obviously I am searching on my own, but if anyone has knowledge I would appreicate knowing it.

 

link: http://www.biochem.uwo.ca/meds/medna/snRNA.html

[zyncod]

snRNAs serve as recognition molecules for intron splice sites. As far as telomere maintenance, I assume they also serve as recognition molecules to be sure that the repeats are long enough.

[Helix]

So, their role in splicing (of introns) is recognition? Then you're proabably right, what else is there to recognize in telomeres? Maybe the sequence; checking if the sequence is correct.

[Yggdrasil]

Telomerase is special among polymerases in that it can synthesize DNA without a template. It is able to do this because telomerase is actually a ribonucleoprotein -- a combination of protein and RNA. Telomerase contains a ~150 nucleotide RNA subunit which serves as a template for the telomere sequence. With this internal RNA template, telomerase can accurately extend the telomere sequence and help maintain the chromosomes' telomeres.

[Helix]

Right, but what role does snRNA play? How does it fit in the telomerase picture. Maybe, and this is a theory, it doesn't play into telomerase but into ALT, the alternative to telomerase. That's a possibility, but not much is known about the ALT pathway.

[Yggdrasil]

The RNA subunit in telomerase is a small nuclear RNA.

[Helix]

Oh is it? I had heard it as "RNA subunit" but never more than that. Thanks.

[rakuenso]

chemically and structurally speaking, how is snRNA different from mature mRNA?

[Helix]

That's a good question. I would assume the molecules accomponying the RNA would be different. I mean, it's sort of like asking what's different between apples and oranges. They just are.

[Yggdrasil]

chemically and structurally speaking, how is snRNA different from mature mRNA?

 

Here are some major differences between snRNAs and mature mRNAs:

 

1) Size. Mature mRNAs are generally around ~1kb (the size of a typical gene), while snRNAs are much smaller (~100bp), hence the name small nuclear RNAs.

 

2) Localization. Mature mRNAs are produced in the nucleus, but are exported into the cytoplasm for translation. snRNAs are found solely in the nucleus (hence the name, small nuclear RNAs).

 

3) Structure. Mature mRNAs (in eukaryotes) have a 5' cap and a 3' poly(A) tail, whereas snRNAs may have other modifications (depending on their function).

 

4) Function. Mature mRNAs eventually associate with ribosomes in order to direct the synthesis of a specific polypeptide. snRNAs will generally associate with nuclear proteins to perform some other function (e.g. pre-mRNA splicing or telomere maintainance).

[Helix]

Wow great info Yggdrasil.