usually found in fungi and single-cell organisms <12: in Acanthamoeba 25 genes
||Bürglin TR, Affolter M. Homeodomain proteins: an update. Chromosoma. 2016 Jun125(3):497-521. doi: 10.1007/s00412-015-0543-8 p.498 left column 3rd paragraphPubMed ID26464018
||Derelle R, Lopez P, Le Guyader H, Manuel M. Homeodomain proteins belong to the ancestral molecular toolkit of eukaryotes. Evol Dev. 2007 May-Jun9(3):212-9 DOI: 10.1111/j.1525-142X.2007.00153.x AND Clarke M et al., Genome of Acanthamoeba castellanii highlights extensive lateral gene transfer and early evolution of tyrosine kinase signaling. Genome Biol. 2013 Feb 1 14(2):R11. doi: 10.1186/gb-2013-14-2-r11PubMed ID17501745, 23375108
||Primary source Derelle et al., 2007 abstract: "Taking advantage from the recent burst of sequence data from a wide variety of eukaryote taxa, [investigators] show here that HD (Homeodomain)-containing transcription factors were already existing and diversified (in at least two main classes) in the last common eukaryote ancestor." Primary source Clarke et al., 2013 abstract: "Here [investigators] present an analysis of a whole genome assembly of Acanthamoeba castellanii (Ac) the first representative from a solitary free-living amoebozoan."
||P.498 left column 3rd paragraph: "In fungi and single-cell organisms, the number tends to be small, usually less than a dozen (primary source Derelle et al. 2007), but in Acanthamoeba, the homeobox family has expanded to 25 (primary source Clarke et al. 2013)."