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[Noob Question] Related to nucleotide sequence DB

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[Noob Question] Related to nucleotide sequence DB

Postby bbs_r » Fri Mar 31, 2006 11:21 am

Hi, please look at the image I captured below. The red circle is the region where I believe the nucleotide sequence references are.

Something does not make sense to me is:
Why there are so many different sequences for one protein?
(All these sequences are talking about one protein)

The protein I am looking at is VAPA_MOUSE (Q9WV55),
Thank you!
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Postby sdekivit » Fri Mar 31, 2006 1:11 pm

alternative splicing
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Postby Trev » Fri Mar 31, 2006 10:57 pm

=> redundancy of a gene code

sdekivit,
it cannot be alternative splicing, because when it is used, some number of different proteins will be produced. but bbs_r said, that all sequences produce one protein.
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Postby Mjhavok » Sat Apr 01, 2006 7:46 pm

I don't entirely understand this question. Can you elabourate please?
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Postby Trev » Sat Apr 01, 2006 8:06 pm

Mjhavok wrote:I don't entirely understand this question. Can you elabourate please?


"Why there are so many different sequences for one protein?"
- do you understand this question? I really hope, yes.
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Postby Mjhavok » Sat Apr 01, 2006 10:35 pm

If you mean why are some protein sequences coded from different nucleotides its because the codon (nucleotide triplet) that codes for each amino acid isn't unique. Each amino has a few codons that can code for it except methionine which is just AUG as its the start codon.

Other than this I do not know if proteins can be made from different amino acid sequences. I think they would not be the same if they did but perhaps in same series as some amino acids are similar and have simlar properties they might not effect the overall structure of the protein if 1 amino acid was swaped for a similar amino acid with similar structure and charge. In cases of sickle cell anemia changing 1 amino acid in haemoglobin alters the protein quite a bit.

Hope my ramble helps. I'm off to tell my lecturer there is a contradiction in 2 textbooks I have (how sad am I) lol.
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Postby bbs_r » Tue Apr 04, 2006 7:33 am

Trev wrote:
Mjhavok wrote:I don't entirely understand this question. Can you elabourate please?


"Why there are so many different sequences for one protein?"
- do you understand this question? I really hope, yes.


Sorry for my poor English. What I mean is:
When I clicked on a protein file in the database, the file shows me its sequence, function and etc. But I just curious that why there are more than one entry of those "EMBL cross references", say
"AF157497; AAD45020.1; mRNA" <--- what are these kind of things? What did these things tell me?


Thank you very much!
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Postby Trev » Tue Apr 04, 2006 5:19 pm

"Why there are so many different sequences for one protein?"

because 1 aminoacid is coded by several sequences. for example: Serin is coded by UCA, UCG, UCC, UCU; Tyrosine = UAU, UAC. this phenomenon called redundancy of a gene code.
That`s why bbs_r had saw not one nucleotide sequence for one protein sequence.
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Postby bhupesh » Fri Jun 09, 2006 11:28 am

in the picture shown the no ADF9089 or something like that which is shown is not theprotien sequence. it is the accession code of that protien with is given to identify it in databases like GENBANK . so if u want the sequence of that protein take that code and go to te site http://www.ncbi.nlm.nih.gov and search for it.
thanks...
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