Opsins contain seven transmembrane α-helical domains connected by three extra-cellular and three cytoplasmic loops.

The picture represents the fourth cytoplasmic loop of the CB cannabinoid receptor.

The best conserved region is a stretch of 12 residues which are located in a cytoplasmic loop between the second and third transmembrane domains.

The guanylate kinase domain of the β subunit binds to the α subunit I-II cytoplasmic loop and regulates HVGCC activity.

All glucose transporters including Snf3 contain an arginine residue situated in a cytoplasmic loop preceding the fifth transmembrane domain.

Two transmembrane domains of p7 are connected by a cytoplasmic loop and are oriented towards the endoplasmic reticulum's lumen.

Both types of protein consist of a cytoplasmic N-terminal domain, followed by four transmembrane segments that delimit two extracellular and one cytoplasmic loops; the C- terminal domain is cytoplasmic.

Presenilins undergo cleavage in an alpha helical region of one of the cytoplasmic loops to produce a larger N-terminal and a smaller C-terminal fragment that together form part of the functional protein.

This region seems to be located in a cytoplasmic loop between two transmembrane domains.

These correspond to a putative palmitoylation site which allows formation of a 'fourth cytoplasmic loop' that maybe involved in G-protein coupling.