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shenfei-

铜虫 (小有名气)

[交流] 【求助/交流】“ low-complexity regions masked by SEG ”是什么意思?

在ExPASY上比对氨基酸序列时,出现了个“ low-complexity regions masked by SEG ”,是什么意思?“low-complexity regions”是什么意思?“SEG”又是什么意思?


谢谢大家指点
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shenfei-

铜虫 (小有名气)

自己先顶一个……
走别人的路,只能让自己无路可走;走自己的路,让别人跟着走
2楼2010-10-25 17:02:31
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brightfuture01

木虫之王 (文坛精英)

我爱打老虎

文献杰出贡献

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shenfei-(金币+1):谢谢…… 2010-10-25 17:55:03
dhd997(金币+2):热心鼓励。 2010-10-25 18:10:17
SEG:A program for filtering low complexity regions in amino acid sequences. Residues that have been masked are represented as "X" in an alignment. SEG filtering is performed by default in the blastp subroutine of BLAST 2.0. (Wootton and Federhen

low-complexity regions :是指低复杂度区域,和重复序列相类似。

看下面这段话:Many nucleotide and amino acid sequences are highly repetitive in nature. If your query sequence contains regions of low complexity or repeats, you can end up with many non-related, high scoring sequences being found during BLAST (or FASTA) searches (e.g. hits against proline-rich regions or poly-A tails). In other cases, your sequence may contain regions of vector sequence, or repeat regions such as Alu sequences, that you either do not want included in your sequence, or at the very least, wish to have discluded in any searches you carry out based on sequence similarity.

Programs have been devised to filter out unwanted segments of sequence from within a larger sequence. For example, filtering low complexity or repeat regions out of your query sequence before searching a database can reduce the reporting of un-related sequences that match by chance. Filtering works by running programs that identify regions containing particular types of sequences. These regions are replaced with a series of N's (in the case of nucleotide sequences), or X's (in the case of peptide sequences). One N or one X replaces each residue in the region.

详细来源请看:http://www.molbiol.ox.ac.uk/anal ... AST_filtering.shtml
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3楼2010-10-25 17:53:35
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