SUMOylation and calcium signalling: potential roles in the brain and beyond.

Small ubiquitin-like modifier (SUMO) conjugation (or SUMOylation) is a post-translational protein modification implicated in alterations to protein expression, localization and function. Despite a number of nuclear roles for SUMO being well characterized, this process has only started to be explored in relation to membrane proteins, such as ion channels. Calcium ion (Ca) signalling is crucial for the normal functioning of cells and is also involved in the pathophysiological mechanisms underlying relevant neurological and cardiovascular diseases. Intracellular Ca levels are tightly regulated; at rest, most Ca is retained in organelles, such as the sarcoplasmic reticulum, or in the extracellular space, whereas depolarization triggers a series of events leading to Ca entry, followed by extrusion and reuptake. The mechanisms that maintain Ca homoeostasis are candidates for modulation at the post-translational level. Here, we review the effects of protein SUMOylation, including Ca channels, their proteome and other proteins associated with Ca signalling, on vital cellular functions, such as neurotransmission within the central nervous system (CNS) and in additional systems, most prominently here, in the cardiac system.