The Directed Movement of Substances (such As Macromolecules Small Molecules Ions) Into Out of or Within a Cell or Between Cells or Within a Multicellular Organism by Means of Some Agent Such As a Transporter or Pore.
The Component of a Membrane Consisting of Gene Products and Protein Complexes That Have Some Part That Penetrates At Least One Leaflet of the Membrane Bilayer. This Component Includes Gene Products That Are Buried in the Bilayer with No Exposure Outside the Bilayer.
Interacting Selectively and Non Covalently with a Nucleotide Any Compound Consisting of a Nucleoside That Is Esterified with (ortho)phosphate or an Oligophosphate At Any Hydroxyl Group On the Ribose or Deoxyribose.
Catalysis of the Transfer of Substances Sized Less Than 1000 Da From One Side of the Membrane to the Other. the Transmembrane Portions of Porins Consist Exclusively of Beta Strands Which Form a Beta Barrel. They Are Found in the Outer Membranes of Gram Negative Bacteria Mitochondria Plastids and Possibly Acid Fast Gram Positive Bacteria.