"A heterodimer with protein serine/threonine phosphatase activity that is polycation-stimulated (PCS), being directly stimulated by protamine, polylysine, or histone H1; it constitutes a subclass of several enzymes activated by different histones and polylysine, and consists of catalytic and regulatory subunits [goid 159] [pmid 8206937] [evidence TAS]; A membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. In most cells, the nucleus contains all of the cell's chromosomes except the organellar chromosomes, and is the site of RNA synthesis and processing. In some species, or in specialized cell types, RNA metabolism or DNA replication may be absent [goid 5634] [pmid 11256614] [evidence IDA]; A semiautonomous, self replicating organelle that occurs in varying numbers, shapes, and sizes in the cytoplasm of virtually all eukaryotic cells. It is notably the site of tissue respiration [goid 5739] [evidence IEA]; The protein complexes that form the mitochondrial electron transport system (the respiratory chain), associated with the inner mitochondrial membrane. Complexes I, III and IV can transport protons if embedded in an oriented membrane, such as an intact mitochondrial inner membrane [goid 5746] [evidence IEA]; The region between the inner and outer lipid bilayers of the mitochondrial envelope [goid 5758] [pmid 8689682] [evidence TAS]; The gel-like material, with considerable fine structure, that lies in the matrix space, or lumen, of a mitochondrion. It contains the enzymes of the tricarboxylic acid cycle and, in some organisms, the enzymes concerned with fatty-acid oxidation [goid 5759] [evidence IEA]; That part of the cytoplasm that does not contain membranous or particulate subcellular components [goid 5829] [pmid 8689682] [evidence IMP]; That part of the cytoplasm that does not contain membranous or particulate subcellular components [goid 5829] [pmid 9267021] [evidence EXP]; That part of the cytoplasm that does not contain membranous or particulate subcellular components [goid 5829] [pmid 9922454] [evidence EXP]; That part of the cytoplasm that does not contain membranous or particulate subcellular components [goid 5829] [pmid 9390557] [evidence EXP]"