Colipase

Colipase, abbreviated CLPS, is a protein co-enzyme that counteracts the inhibitory effect of intestinal bile acid on the enzymatic activity of pancreatic lipase. It is secreted by the pancreas in an inactive form, procolipase, which is activated in the intestinal lumen by trypsin.

Intestinal bile acids (which aid lipid digestion by facilitating micelle formation) adhere to the surface of emulsified fat droplets, displacing lipase (which is only active at the water-fat interface) from the droplet surface. Colipase acts as a bridging molecule, binding to both lipase and bile acids, thus anchoring lipase onto the droplet surface, preventing its displacement.

In humans, the colipase protein is encoded by the CLPS gene.

Protein domain

Colipase is also a family of evolutionarily related proteins.

Colipase is a small protein cofactor needed by pancreatic lipase for efficient dietary lipid hydrolysis. Efficient absorption of dietary fats is dependent on the action of pancreatic triglyceride lipase. Colipase binds to the C-terminal, non-catalytic domain of lipase, thereby stabilising an active conformation and considerably increasing the hydrophobicity of its binding site. Structural studies of the complex and of colipase alone have revealed the functionality of its architecture.

Colipase is a small protein (12K) with five conserved disulphide bonds. Structural analogies have been recognised between a developmental protein (Dickkopf), the pancreatic lipase C-terminal domain, the N-terminal domains of lipoxygenases and the C-terminal domain of alpha-toxin. These non-catalytic domains in the latter enzymes are important for interaction with membrane. It has not been established if these domains are also involved in eventual protein cofactor binding as is the case for pancreatic lipase.

Colipase N-terminal domain File:PDB 1lpb EBI.jpg Structure of the pancreatic lipase-colipase complex inhibited by a C11 alkyl phosphonate. Identifiers Symbol Colipase Pfam PF01114 InterPro IPR001981 PROSITE PDOC00111 SCOP2 1lpb / SCOPe / SUPFAM CDD cd00039 Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary PDB 1eth​, 1lpa​, 1lpb​, 1n8s​, 1pcn​, 1pco​

Colipase C-terminal domain
File:PDB 1pcn EBI.jpg solution structure of porcine pancreatic procolipase as determined from 1h homonuclear two-and three-dimensional nmr
Identifiers
Symbol	Colipase_C
Pfam	PF02740
InterPro	IPR017914
PROSITE	PDOC00111
SCOP2	1lpb / SCOPe / SUPFAM
CDD	cd00039
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

See also

• Enterostatin

External links

• Colipases at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
• PDBe-KB provides an overview of all the structure information available in the PDB for Pig Colipase

This article incorporates text from the public domain Pfam and InterPro: IPR001981