The review describes the mechanisms of function and regulation of store-operated (so called SOC) channels and their connections with different intracellular calcium regulating structures. The function of both ryanodine sensitive and inisitol-1,3-phosphate sensitive endoplasmic reticulum are presented. The mechanisms of their connections with mitochondria and potential-activated channels are shown. Main attention is concentrated on compensatory calcium entry (CCE) connected with depletion of endoplasmic reticulum, the role of different transient receptor potential (TRP) channels in this process and possible mechanisms of their activation.