A2 holin family

The Putative Archaeal 2 TMS Holin Family consists of a few putative holins from Nitrososphaerota ranging in size from about 130 to 165 amino acyl residues and exhibiting 2 transmembrane segments. A representative list of proteins belonging to the A2-Hol family can be found in the . The archaeon, Candidatus Nitrosoarchaeum limnia, encodes adjacent genes designated Toxin Secretion/Lysis Holin. The "toxin" gene encodes a soluble protein of 325 aas stated as belonging to the "Glycosyltransferase GBT-type Superfamily". This protein brings up other glycosyltransferases in a NCBI BLAST search. The adjacent gene encodes a small protein of 132 aas and 2 TMSs that could be a holin, based on its size and topology. This protein has the UniProt accession number of . Paralogues are found in this same organism and other closely related species.