Insulin secretion from intact mouse pancreatic islets was investigated with two-photon excitation imaging. Insulin granule exocytosis occurred mainly toward the interstitial space, away from blood vessels. The fusion pore was unusually stable with a lifetime of 1.8 seconds. Opening of the 1.4-nanometer-diameter pore was preceded by unrestricted lateral diffusion of lipids along the inner wall o...

In interphase eukaryotic cells, the nucleus is separated from the cytoplasm by a double nuclear membrane system called the nuclear envelope. The nuclear envelope enables the two cell compartments to have their distinct composition, and separates the genetic machinery from protein synthesis. Molecular exchange between the nucleus and the cytoplasm, however, is essential for keeping eukaryotic ce...