| Primary Identifier | IPR036668 | Type | Homologous_superfamily |
| Short Name | Antifreeze_sf |
| description | Antifreeze proteins (AFPs) are a class of proteins that are able to bind to and inhibit the growth of macromolecular ice, thereby permitting an organism to survive subzero temperatures by decreasing the probability of ice nucleation in their bodies []. These proteins have been characterised from a variety of organisms, including fish, plants, bacteria, fungi and arthropods. This entry represents insect AFPs of the type found in spruce budworm, Choristoneura fumiferana.The structure of these AFPs consists of a left-handed β-helix with 15 residues per coil []. The β-helices of insect AFPs present a highly rigid array of threonine residues and bound water molecules that can effectively mimic the ice lattice. As such, β-helical AFPs provide a more effective coverage of the ice surface compared to the α-helical fish AFPs.A second insect antifreeze from Tenebrio molitor () also consists of β-helices, however in these proteins the helices form a right-handed twist; these proteins show no sequence homology to the current entry, but may act by a similar mechanism. The β-helix motif may be used as an AFP structural motif in non-homologous proteins from other (non-fish) organisms as well. |
