"The irregular network of unit membranes, visible only by electron microscopy, that occurs in the cytoplasm of many eukaryotic cells. The membranes form a complex meshwork of tubular channels, which are often expanded into slitlike cavities called cisternae. The ER takes two forms, rough (or granular), with ribosomes adhering to the outer surface, and smooth (with no ribosomes attached) [goid 5783] [pmid 11256614] [evidence IDA]; The membrane surrounding a cell that separates the cell from its external environment. It consists of a phospholipid bilayer and associated proteins [goid 5886] [evidence ISS]; Penetrating at least one phospholipid bilayer of a plasma membrane. May also refer to the state of being buried in the bilayer with no exposure outside the bilayer [goid 5887] [pmid 2864289] [evidence TAS]; The side of the plasma membrane that is opposite to the side that faces the cytoplasm [goid 9897] [evidence ISS]; The migrating motile tip of a growing nerve cell axon or dendrite [goid 30426] [evidence ISS]; Tethered to a membrane by a covalently attached anchor, such as a lipid moiety, that is embedded in the membrane. When used to describe a protein, indicates that none of the peptide sequence is embedded in the membrane [goid 31225] [evidence IEA]; Tethered to the plasma membrane by a covalently attached anchor, such as a lipid moiety, that is embedded in the membrane, with the bulk of the gene product located on the side opposite to the side that faces the cytoplasm. When used to describe a protein, indicates that the peptide sequence does not span the membrane [goid 31362] [evidence IEA]; Any of the small (10-200 nm), heterogeneous, highly dynamic, sterol- and sphingolipid-enriched membrane domains that compartmentalize cellular processes. Small rafts can sometimes be stabilized to form larger platforms through protein-protein and protein-lipid interactions [goid 45121] [pmid 15093746] [evidence NAS]; The part of a cell or its extracellular environment in which a gene product is located. A gene product may be located in one or more parts of a cell and its location may be as specific as a particular macromolecular complex, that is, a stable, persistent association of macromolecules that function together [goid 5575] [evidence ND ]"