The Sigma Receptor 1 (sig-1R) is a protein present in numerous normal tissues, such as brain, retina, lens, liver,
lung, heart, but also in many tumor lines. Its amino acid sequence is homologous to fungal C-8,7 sterol isomerase, but it
has no known homology with mammalian proteins and does not possess sterol isomerase activity. It is localized in plasma
and ER membranes, and its exact function is not clarified as of yet. Last reports point to its participation in regulation of
ionic channels activity, particularly calcium channels. Application of numerous synthetic ligands of sigma1 receptor provided
means to study its protective effects and metabolic functions in different tissues. This review describes influence of
sigma1 receptor on various aspects of cellular metabolism, such as calcium signalling, mitochondrial functions, oxidative
stress, survival and apoptotic pathways, and tumor cells proliferation.