PROSITE documentation PDOC00111

Colipase family signature and profile

Colipase [1,2,3] is a protein that functions as a cofactor for pancreatic lipase, with which it forms a stoichiometric complex. It also binds to the bile-salt covered triacylglycerol interface thus allowing the enzyme to anchor itself to the water-lipid interface.

As shown in the following schematic representation, colipase is a small protein of approximately 100 amino-acid residues with five conserved disulfide bonds.

                           +--------+
                        +--|--+     |    +----------+
                        |  |  |     |    |   *****  |
                xxxxxxxxCxxCxCCxxxxxCxxxxCxxxxxCxCxxCxxxxxxxxCxxxx
                             |                 | |           |
                             +-----------------+ +-----------+

'C': conserved cysteine involved in a disulfide bond.
'*': position of the pattern.

As a signature pattern for this family, we chose a region which includes two of the cysteines involved in disulfide bonds, as well as three tyrosine residues which seem to be involved in the interfacial binding. We also developed a profile that covers the whole colipase.