Why does this stop gained result in a longer protein than the canonical version

Question

[curious]

rs202181505 is a stop gain in G6PD resulting in protein change ENSP00000358633.2.

ENSP00000358633.2 is 561 aa long protein w/ transcript length of 2223 bp.

The ensembl canonical G6PD (ENST00000393562.10) is 515 aa long protein w/ a transcript length of 1799 bp

I dont get how ENSP00000358633.2 has a stop gained and a shorter transcript compared to the canonical ENST00000393562.10 but more amino acids. Can anyone help me understand?

Answer 1

[Ram]

rs202181505 is a stop gain in G6PD resulting in protein change ENSP00000358633.2.

You're misreading the effects. It results in the change p.Gly266Ter on the protein ENSP00000358633.2 - it stops the protein at residue 266. It does not result in an alternate splice-form - coding mutations don't result in alternate splice-forms.

The stop-gained is happening to one isoform, it does not result in a different isoform, just that isoform being terminated early. If you're wondering why a "canonical" transcript is not the longest transcript, that is not impossible. A bunch of genes have canonical isoforms that are not the longest isoform, because these isoforms are the ones most widely studied. See BRCA1, ESR1, etc.

[curious]

that makes a lot more sense