MBOAT

The MBOAT (membrane bound O-acyl transferase) family of membrane proteins is a family of various acyltransferase enzymes. All family members contain multiple transmembrane domains and most carry two conserved residues, a conserved histidine (His) embedded in a hydrophobic stretch of residues and an asparagine (Asn) or histidine within a more hydrophilic region some 30-50 residues upstream.

MBOAT enzymes catalyze the transfer of an acyl group from an acyl-coenzyme or accessory protein to one of several different substrates. The family is found from bacteria to eukaryotes.

The family may be grouped into three categories, according to function:
 * 1) enzymes involved in neutral lipid biosynthesis;
 * 2) enzymes involved in protein/peptide acylation;
 * 3) enzymes involved in phospholipid re-modelling.

Structure
The structure for one MBOAT protein, DltB from Streptococcus thermophilus, has been solved. DltB performs D-alanylation of cell-wall teichoic acid. It contains a ring of 11 transmembrane helices surrounding a tunnel that goes through the biological membrane. The tunnel connects to a partner, DltC, which carries the D-alanine to the conserved histidine residue of DltB MBOAT located at the bottom of the funnel. A computational model of human ghrelin O-acyltransferase (GOAT) (Q96T53) revealed a transmembrane channel that facilitates octanoylation of the peptide hormone ghrelin. DltB and GOAT share structural similarities in their homologous regions, suggesting a common core fold for MBOAT family members.