[ensembl-dev] Understanding Transcripts.

Allan Kamau kamauallan at gmail.com
Mon Jun 4 08:02:37 BST 2012

I am a non-biologist and I would like to get better understanding of a
transcript in relation to a gene.
According to a search on Ensembl, the gene "ENSG00000133997" reports
that it has 11 transcripts and a listing of transcript_ids of these
transcripts is provided. Some of the entries in this transcript
listing have protein product ids and advises that "A protein coding
transcript is a spliced mRNA that leads to a protein product" and the
other entries are described as "No protein product" and have the text
"Retained intronNoncoding transcript containing intronic sequence"
along side them.

My initial understanding was as follows (which I now think is wrong).
One transcript is one mature mRNA which is composed of one or more
exons observed to join together and have a polyA tail. And that this
single transcript would be translated into a protein based gene. There
could be several such transcripts (for different situations) all
producing perhaps different protein products but each of these protein
products is independently a variant of the the same gene to which
these transcripts are known to yield.

Or one transcript could be composed of an intron (is it possible to
have multiple introns joined together) that would represent a single
non-protein based (or simply RNA based) gene. And that there could be
multiple such transcripts yielding the same gene (may have different
structure but performs the same function).
And that a gene may either be enzyme based or RNA based, which means
that for a given gene we may not have transcripts representing mRNA
and transcripts representing RNA gene products at the same time.

Kindly advise.

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