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A dopamine molecule consists of a catechol structure (a benzene ring with two hydroxyl side groups) with one amine group attached via an ethyl chain. [14] As such, dopamine is the simplest possible catecholamine, a family that also includes the neurotransmitters norepinephrine and epinephrine. [15]
A transmembrane domain (TMD, TM domain) is a membrane-spanning protein domain.TMDs may consist of one or several alpha-helices or a transmembrane beta barrel.Because the interior of the lipid bilayer is hydrophobic, the amino acid residues in TMDs are often hydrophobic, although proteins such as membrane pumps and ion channels can contain polar residues.
This difference is due to the different methods used to measure hydrophobicity. The method used to obtain the Janin and Rose et al. scales was to examine proteins with known 3-D structures and define the hydrophobic character as the tendency for a residue to be found inside of a protein rather than on its surface.
The biological membrane is made up of lipids with hydrophobic tails and hydrophilic heads. [6] The hydrophobic tails are hydrocarbon tails whose length and saturation is important in characterizing the cell. [7] Lipid rafts occur when lipid species and proteins aggregate in domains in the membrane. These help organize membrane components into ...
Fluid mosaic model of a cell membrane. The fluid mosaic model explains various characteristics regarding the structure of functional cell membranes.According to this biological model, there is a lipid bilayer (two molecules thick layer consisting primarily of amphipathic phospholipids) in which protein molecules are embedded.
Schematic representation of the different types of interaction between monotopic membrane proteins and the cell membrane: 1. interaction by an amphipathic α-helix parallel to the membrane plane (in-plane membrane helix) 2. interaction by a hydrophobic loop 3. interaction by a covalently bound membrane lipid (lipidation) 4. electrostatic or ...
The two scientists proposed a structure for this bi-layer, with the polar hydrophilic heads facing outwards towards the aqueous environment and the hydrophobic tails facing inwards away from the aqueous surroundings on both sides of the membrane. Although they arrived at the right conclusions, some of the experimental data were incorrect such ...
The lipophilic group is typically a large hydrocarbon moiety, such as a long chain of the form CH 3 (CH 2) n, with n > 4. The hydrophilic group falls into one of the following categories: [citation needed] charged groups anionic. Examples, with the lipophilic part of the molecule represented by R, are: carboxylates: RCO 2 −; sulfates: RSO 4 −