Antifreeze solenoids

Insect antifreeze protein flat /8-solenoid with T-type cross section ... 

The repeat sequences in solenoid proteins are often so imperfect that it is difficult to identify them without knowledge of the 3D structure or other supplementary information. In highly regular /1-solenoids, such as antifreeze proteins (Leinala et al., 2002 Liou et al., 2000) or YadA adhesin (Nummelin et al., 2004), the repeats are of the same length and sequence similarity between the repeats is discernible (so-called overt repeats). Frequently, however, the repeats in a given /1-solenoid vary in length because additional residues may be inserted at turn sites without disrupting the pattern of /1-strands that stabilizes the structure (Steinbacher et al., 1994 Yoder et al., 1993). In these cases, the structural repeats are not apparent as sequence repeats (covert repeats). 

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