The MBOAT (membrane bound ''O''-acyl transferase) family of membrane proteins is a family of various acyltransferase

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

s. All family members contain multiple transmembrane domains and most carry two conserved residues, a conserved

histidine Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an Amine, α-amino group (which is in the protonated –NH3+ form under Physiological condition, biological conditions), a carboxylic ...

(His) embedded in a

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

stretch of residues and an

asparagine Asparagine (symbol Asn or N) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), an α-carboxylic acid group (which is in the depro ...

(Asn) or histidine within a more

hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are n ...

region some 30-50 residues upstream. MBOAT enzymes catalyze the transfer of an

acyl In chemistry, an acyl group is a moiety derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids. It contains a double-bonded oxygen atom and an organyl group () or hydrogen in the case of formyl grou ...

group from an acyl-coenzyme or accessory protein to one of several different substrates. The family is found from

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

eukaryotes The eukaryotes ( ) constitute the domain of Eukaryota or Eukarya, organisms whose cells have a membrane-bound nucleus. All animals, plants, fungi, seaweeds, and many unicellular organisms are eukaryotes. They constitute a major group of ...

. The family may be grouped into three categories, according to function: #enzymes involved in neutral lipid biosynthesis; #enzymes involved in protein/peptide acylation; #enzymes involved in

phospholipid Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...

re-modelling.

Structure

The structure for one MBOAT protein, DltB from ''

Streptococcus thermophilus ''Streptococcus thermophilus'' formerly known as ''Streptococcus salivarius ''subsp.'' thermophilus'' is a gram-positive bacteria, gram-positive bacterium, and a lactic acid fermentation, fermentative facultative anaerobic organism, facultative ...

'' (), 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 Ghrelin (; or lenomorelin, INN) is a hormone primarily produced by enteroendocrine cells of the gastrointestinal tract, especially the stomach, and is often called a "hunger hormone" because it increases the drive to eat. Blood levels of ghrel ...

. DltB and GOAT share structural similarities in their homologous regions, suggesting a common core fold for MBOAT family members.

Human proteins with this domain

References

* {{InterPro content, IPR004299 Enzymes Membrane proteins Protein families