{{tag>structure}}
====== Crossover =======

This is a term used to describe one possible type of backbone connection observed between
[[glossary:beta_strand |beta strands]] in which the chain loops around to re-enter the sheet on the opposite end. For [[glossary:beta_sheet | beta sheet]] connectivity, cross over connections are denoted by nx,
where n denotes how many strands it moves over in the sheet and in which direction.
+1x denotes a crossover connection between nearest neighbours, +2x
denotes a crossover connection that misses one intervening strand in the sheet, and so on. The term
'crossover' has also been extended to include crossover loops which connect two sequential [[glossary:alpha_helix | alpha helices]]
that lie parallel in three dimensions.

The example shown is a transferase (CATH domain ID 1rwiA00)).

{{cath:feature>1rwiA00}}


===== References =====

{{pubmed>long:183204}}
{{pubmed>long:329147}}