Insertion and translocation of proteins into and through membranes.

In prokaryotic and eukaryotic organisms, proteins are efficiently sorted to reach their final destinations in a whole range of subcellular compartments. Targeting is mediated by hydrophobic signal sequences or hydrophilic targeting sequences depending upon the compartment, these sequences being often processed. Proteins cannot be translocated through a membrane in a tightly folded stage, they must have a loose conformation, the so-called 'translocation competent state', which is usually kept through interactions with chaperones.