The members of this family are similar to the hypothetical protein yhhN expressed by E. coli. Many are annotated as possible transmembrane proteins, and in fact they all have a high proportion of hydrophobic residues. A human member of this family, formerly known as TMEM86B, is a lysoplasmalogenase that catalyzes the hydrolysis of the vinyl ether bond of lysoplasmalogen. Putative conserved active site residues have been proposed for the YhhN family.