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Incoming links: Molecular mass
Molecular mass 2026-10-18
The molecular mass is the mass of a molecule; relative molecular mass compares it with a reference mass.
Nuclear pore complex Created 2026-10-14 Updated 2026-10-18
A nuclear pore complex is an assembly of proteins spanning the nuclear envelope and regulating passage between the cell nucleus and cytosol. It is a selective gateway, not simply an unregulated hole: messenger RNA export and import of nuclear proteins require appropriate transport machinery. See Alberts et al.: nuclear pore complexes.
The nuclear pore complex occupies a junction of both nuclear envelope membranes. Its protein scaffold surrounds an aqueous passage connecting cytosol to the cell nucleus, rather than the intermembrane space. Diffusion permits small soluble cargo to pass; selective receptors transport other cargo. Molecular mass alone is not a universal cutoff.[ref]
Molecular Biology of the Cell, 4th edition by Bruce Alberts and others. Nuclear Pore Complexes Perforate the Nuclear Envelope, Figures 12-10–12-11; Nuclear Localization Signals Direct Nuclear Proteins to the Nucleus
The nuclear pore complex bridges both membranes of the nuclear envelope
. Original topology schematic, not a measured structure. The central passage connects cytosol and cell nucleus; cargo does not enter the intermembrane space. Shapes, distances and arrows are illustrative. Details.