Cullin

Cullins are a family of hydrophobic scaffold proteins which provide support for ubiquitin ligases (E3). All eukaryotes appear to have cullins. They combine with RING proteins to form ''Cullin-RING ubiquitin ligases'' (CRLs) that are highly diverse and play a role in myriad cellular processes, most notably protein degradation by ubiquitination.

The human genome contains eight cullin genes * CUL1, part of SCF complex * CUL2, part of ECS complex (Elongin C - CUL2 - SOCS-box) * CUL3, part of CUL3-BTB complex * CUL4A * CUL4B * CUL5 * CUL7 * CUL9, also known as PARC

There is also a more distant member called ANAPC2 (or APC2), part of the Anaphase-promoting complex.

CUL1, 2, 3, 4A, 4B, 5 and 7 each form part of a multi-subunit ubiquitin complex. Provided by Wikipedia