PLB1

PLB1 is a membrane-associated phospholipase that displays lysophospholipase and phospholipase A2 activities through removal of sn-1 and sn-2 fatty acids of glycerophospholipids. In addition, it displays lipase and retinyl ester hydrolase activities. The encoded protein is highly conserved and is composed of a large, glycosylated extracellular domain composed of four tandem homologous domains, followed by a hydrophobic segment that anchors the enzyme to the membrane and a short C-terminal cytoplasmic tail.

Full Name

Phospholipase B1

Function

Calcium-independent membrane-associated phospholipase that catalyzes complete diacylation of phospholipids by hydrolyzing both sn-1 and sn-2 fatty acyl chains attached to the glycerol backbone (phospholipase B activity) (By similarity).
Has dual phospholipase and lysophospholipase activities toward diacylphospholipids. Preferentially cleaves sn-2 ester bonds over sn-1 bonds. Acts as a lipase toward glycerolipid substrates (By similarity).
Hydrolyzes fatty acyl chains of diacylglycerols with preference for the sn-2 position and of triacylglycerols with not positional selectivity (By similarity).
May also hydrolyze long chain retinyl esters such as retinyl palmitate (By similarity).
May contribute to digestion of dietary phospholipids, glycerolipids and retinoids, facilitating lipid absorption at the brush border (By similarity).

Biological Process

Diacylglycerol catabolic processIEA:Ensembl
Phosphatidylcholine acyl-chain remodelingTAS:Reactome
Phosphatidylcholine catabolic processIEA:Ensembl
Phosphatidylethanolamine catabolic processIEA:Ensembl
Phosphatidylglycerol catabolic processIEA:Ensembl
Phospholipid metabolic processManual Assertion Based On ExperimentIBA:GO_Central
Positive regulation of acrosome reactionIEA:Ensembl
Retinoid metabolic processTAS:Reactome
Triglyceride catabolic processIEA:Ensembl

Cellular Location

Apical cell membrane
Present in the intestinal brush border membranes.

Topology

Extracellular: 22-1417
Helical: 1418-1438
Cytoplasmic: 1439-1458

PTM

Undergoes proteolytic cleavage in the ileum.