A hydrophobic ratchet entrenches molecular complexes

[Rumraket (Mikkel R.)]

Yes, fits nicely too with this one:

De novo emergence of adaptive membrane proteins from thymine-rich genomic sequences

Another intriguing de novo gene evolution paper was recently published in Nature Communications: De novo emergence of adaptive membrane proteins from thymine-rich genomic sequences Some excerpts: Mutations that cause changes to the sequence or expression of established genes are typically constrained by preexisting selected effects—the specific physiological processes mediated by the gene products that are maintained by natural selection20. In contrast, emerging proto-genes are expected to mostly lack such constraints because they do not have selected effects. This would leave them more readily accessible to evolutionary changes that have the potential to increase fitness (adaptive changes)3,4. We reasoned that this initial potential for adaptive changes would give way as proto-genes mature and the adaptive changes engender novel selected effects, in turn increasing constraints and reducing the possibility of future change. This reasoning is akin to Sartre’s “existence precedes ess…

Notice this:

In emerging but not established ORFs, beneficial fitness effects are associated with a high propensity to encode transmembrane ™ domains. Analyses of genome-wide TM propensities led us to hypothesize that novel adaptive TM peptides may spontaneously emerge when thymine-rich non-genic regions become translated: a “TM-first” model of gene birth.

And:

Our analyses suggest that a simple thymine bias suffices to generate a diverse reservoir of novel TM peptides (Fig. 5a–c), and that incipient proto-genes with TM domains are more likely to increase fitness than proto-genes without TM domains (Fig. 4).

Seems there’s an intrinsic mutational bias towards hydrophobic proteins.