I am working on a family of metazoan proteins (approximately 400 residues and virtually no indels in the multiple sequence alignments) were all members have 87%, 80%, and 77% identical residues within the vertebrates, chordates and bilateria, respectively. This is sequence identity at the amino acid level, but of course with a large number of synonymous mutations. This seems to be a protein family with a very high degree of conservation/stabilizing selection. Number of nonsyn mutations diveded by number of syn mutations = Ka/Ks is very low here.
In this article, from 2007, http://www.ncbi.nlm.nih.gov/pubmed/17544402 it is claimed that "Hsp70 is, by far, the most conserved protein in evolution" (first sentence in section 2), but the references are from 1985-1994. An awful lot has happened in molecular biology since 1994...
Can anyone point me to a more recent study that asked the question: "What is the most conserved protein in biology?". That is, at the amino acid level, or basically the lowest overall Ka/Ks. I am mainly interested in metazoa.
I can't point to any studies, but a good guess might be histones.
Histones sounds like a good suggestion, but it I would expect that somone actually has done a proper study. On the other hand, I have not yet been able to find anything in the literature.