The Beta-Globin Pseudogene

The Great 2013 Catch-upIn Beta-Globin Pseudogene Is Functional After All (12 April 2013) Jeff Tomkins says… well, it’s in the title, really. This is the older article that Monday’s post alluded to, and it’s really quite similar. Again, we have a pseudogene. Again, it’s been shown that its sequence is being actively preserved by natural selection, as if it were actually useful. Again, it has been found that the pseudogene infact codes for functional RNAs. The biggest difference is that this pseudogene (“HBBP1”) is not a “processed pseudogene” like ψPPM1K was, but that’s not significant here. Continue reading

An Exaptated Pseudogene

Appropriately, for this attempt to return to timely updates, the first new DpSU – Pseudogene Plays Important Role in Cell Cycle, by Jeffrey Tomkins – is again related to junk DNA, just as the last one I did was about ENCODE. This article, however, is of the old type – it’s about a genetic feature, once “dismissed as junk DNA,” that has now been shown to have a function. Or, to quote Tomkins:

Once again, DNA sequence that was once thought to be nothing but a genomic fossil has shown itself to be vital to human survival. In this case, if the so-called pseudogene is not functioning properly, cell cycle dysfunction and cancer is the almost certain outcome.

A pseudogene looks like a gene – often another gene in the same organism – but has lost its original protein-coding function. The pseudogene of interest here is called “ψPPM1K,” and is a processed pseudogene. To make such a gene a normal gene (here, PPM1K) is transcribed into mRNA and the introns are stripped out as normal in the process of protein synthesis. However, instead of progressing further the mRNA is transcribed back into DNA which is inserted back into the chromosome. The result is a partial clone of the original gene, generally lacking introns and possibly other parts. Continue reading