ULP-2 SUMO protease regulates UPR and mitochondrial homeostasis in Caenorhabditis elegans.

Mitochondria are the powerhouses of cells, responsible for energy production and regulation of cellular homeostasis. When mitochondrial function is impaired, a stress response termed mitochondrial unfolded protein response (UPRmt) is initiated to restore mitochondrial function. Since mitochondria and UPRmt are implicated in many diseases, it is important to understand UPRmt regulation.

Phosphatidylinositol (4, 5)-bisphosphate targets double C2 domain protein B to the plasma membrane.

Double C2 domain protein B (DOC2B) is a high-affinity Ca sensor that translocates from the cytosol to the plasma membrane (PM) and promotes vesicle priming and fusion. However, the molecular mechanism underlying its translocation and targeting to the PM in living cells is not completely understood. DOC2B interacts in vitro with the PM components phosphatidylserine, phosphatidylinositol (4, 5)-bisphosphate [PI(4, 5)P ] and target SNAREs (t-SNAREs).

The C2B domain is the primary Ca2+ sensor in DOC2B: a structural and functional analysis.

DOC2B (double-C2 domain) protein is thought to be a high-affinity Ca(2+) sensor for spontaneous and asynchronous neurotransmitter release. To elucidate the molecular features underlying its physiological role, we determined the crystal structures of its isolated C2A and C2B domains and examined their Ca(2+)-binding properties. We further characterized the solution structure of the tandem domains (C2AB) using small-angle X-ray scattering.