Membrane transport protein: Information from Answers.com

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A membrane transport protein (or simply transporter) is a protein involved in the movement of ions, small molecules, or macromolecules, such as another protein across a biological membrane. Transport proteins are integral membrane proteins; that is they exist within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion or active transport.

The mechanism of action of these proteins is known as carrier-mediated transport. There are two forms of carrier-mediated transport, active transport and facilitated diffusion.^[1]

1 Facilitated diffusion
2 More examples
3 See also
4 References
5 External links

Facilitated diffusion

A facilitated diffusion protein speeds the movement of a chemical through a membrane in the absence of energy input; therefore, the transported chemical can move only down a concentration gradient. This can be accomplished by the formation of a high-specificity pore or channel that spans the membrane. These polar "holes" through the membrane are lined by specific amino acids residues that lower the energy barrier to the movement of polar molecules.

More examples

References

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External links

v • d • e Proteins: carrier proteins

Fatty acid	FABP1 · FABP2 · FABP3 · FABP4 · FABP5 · FABP6 · FABP7

Hormone	Follistatin · Growth hormone binding protein · Insulin-like growth factor binding protein (IGFBP1, IGFBP2, IGFBP3, IGFBP4, IGFBP5, IGFBP6, IGFBP7) · Neurophysins (Neurophysin I, II) Sex hormone binding globulin/Androgen binding protein · Transcortin · Thyroxine-binding globulin · Transthyretin

Metal/element	calcium (Calcium-binding protein, Calmodulin-binding proteins) · copper (Ceruloplasmin) · iron (Iron-binding proteins, Transferrin receptor)

Vitamin	Retinol binding protein (4) · Transcobalamin

Other	Acyl carrier protein · Adaptor protein · Cholesterylester transfer protein · F-box protein · GTP-binding protein · Latent TGF-beta binding protein · Light-harvesting complex · Membrane transport protein

Membrane proteins, carrier proteins: membrane transport proteins

ABC-transporter

A1 · A2 · A3 · A4 · A7 · A8 · A12

B1 · B2-3 · B2 · B3 · B4 · B5 · B6 · B7 · B9 · B11

C1 · C2 · C3 · C4 · C5 · C6 · C8-9 (C8, C9) · C10 · C11 · C13

D1 · D2 · D3 · D4 · E1 · F1 · F2

G1 · G2 · G4 · Sterolin (G5 · G8)

Solute carrier

1-10	1A1-7 · 1A1 · 1A2 · 1A3 · 1A4 · 1A5 Glucose transporter: 2A1 (GLUT1) · 2A2 (GLUT2) · 2A3 (GLUT3) · 2A4 (GLUT4) · 2A5 (GLUT5) · 2A6 (GLUT6) · 2A8 (GLUT8) · 2A9 · 2A10 · 2A12 3A1 · 3A2 · 4A1 · 4A2 · 4A3 · 4A4 · 4A5 · 4A7 · 4A8 · 4A11 · 5A1-2 · 5A1 · 5A3 · 5A5 · 5A8 · 6A1 · 6A2 · 6A3 · 6A4 · 6A5 · 6A8 · 6A9 · 6A18 · 6A19 · 6A20 · 7A1 · 7A2 · 7A3 · 7A4 · 7A5 · 7A7 · 7A8 · 7A9 · 7A11 · 8A1-3 · 9A1 · 9A2 · 9A3 · 9A3R1 · 9A3R2 · 9A5 · 9A6 · 9A8 · 10A1 · 10A2 · 10A3 · 10A7

11-20	11A1 · 11A2 · 11A3 · 12A1-2 · 12A3 · 12A4 · 12A5 · 12A6 · 12A7 · 14A1 · 13A3 · 14A2 · 15A1 · 15A2 · 16A1 · 16A2 · 16A3 · 16A4 · 17A1 · 17A5 · 17A6-8 · 17A7 · 18A1 · 18A2 · 18A3 · 19A1 · 19A2 · 19A3 · 20A1 · 20A2

21-30	22A1 · 22A2 · 22A3 · 22A4 · 22A5 · 22A6 · 22A7 · 22A9 · 22A11 · 22A12 · 22A18 · 23A1 · 23A2 · 24A1-2 · 24A5 · 25A1 · 25A3 · 25A4-6 (25A4, 25A6), 25A8 · 25A10 · 25A11 · 25A12 · 25A13 · 25A14 · 25A15 · 25A17 · 25A19 · 25A20 · 25A27 · 25A31 · 25A37 · 25A39 · 26A2 · 26A3 · 26A4 · 26A5 · 26A6 · 26A7 · 26A8 · 27A1 · 27A2 · 27A3 · 27A4 · 28A1 · 28A2 · 29A1 · 29A2 · 29A4 · 30A1 · 30A4 · 30A7 · 30A8

31-40	31A1 · 31A2 · 32A1 · 34A1 · 34A2 · 34A3 · 35A1 · 35A2 · 35B2 · 35B4 · 35C1 · 36A1 · 36A2 · 37A4 · 38A2 · 38A3 · 39A1 · 39A2 · 39A3 · 39A4 · 39A6 · 39A7

41-47	40A1 · 42A1 · 42A2 · 42A3 · 43A1 · 44A1 · 44A2 · 44A4 · 45A2 · 46A1 · 47A1 · 47A2

O	O1A2 · O1B1 · O1B3 · O2B1 · O431 · O4A1

Other

Amino acid (CD98) · Fatty acid (CD36) · Ion channels · Ion pumps · Mitochondrial membrane transport protein · Neurotransmitter transport proteins · Nuclear (Importin · Karyopherin)

Membrane transport protein: ion channels

Ca²⁺: Calcium channel

Voltage-gated	L-type/Ca_vα (1.1, 1.2, 1.3, 1.4) · N-type/Ca_vα2.2 · P-type/Ca_vα(2.1) · Q-type/Ca_vα2.1 · R-type/Ca_vα2.3 · T-type/Ca_vα(3.1, 3.2, 3.3) α₂δ-subunits (1, 2) · β-subunits (β1, β2, β3, β4) · γ-subunits (γ1, γ2, γ3, γ4) Cation channels of sperm (1, 2, 3, 4) · Two-pore channel (1, 2)

Ligand-gated	Inositol trisphosphate receptor (1, 2, 3) · Ryanodine receptor (1, 2, 3)

Na⁺: Sodium channel

Voltage-gated	Na_vα (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 7A) · Na_vβ (1, 2, 3, 4)

Constitutively active	Epithelial sodium channel (α, β, γ, δ)

K⁺: Potassium channel

Voltage-gated	K_vα1-6 (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.10) · (2.1, 2.2) · (3.1, 3.2, 3.3, 3.4) · (4.1, 4.2, 4.3) · (5.1) · (6.1, 6.2, 6.3, 6.4) K_vα7-12 (7.1, 7.2, 7.3, 7.4, 7.5) · (8.1, 8.2) · (9.1, 9.2, 9.3) · (10.1, 10.2) · (11.1/hERG, 11.2, 11.3) · (12.1, 12.2, 12.3) K_vβ (1, 2, 3) · KCNIP (1, 2, 3, 4) · minK/ISK · minK/ISK-like · MiRP (1, 2, 3) · Shaker gene

Calcium-activated	BK channel (α1, β1, β2, β3, β4) · SK channel (SK1, SK2, SK3, SK4) · K_Ca (1.1, 2.1, 2.2, 2.3, 3.1, 4.1, 4.2, 5.1)

Inward-rectifier	K_ir (1.1, 2.1, 2.2, 2.3, 2.4) · GIRK/K_ir (3.1, 3.2, 3.3, 3.4) · K_ir (4.1, 4.2, 5.1, 6.1, 6.2, 7.1)

Tandem pore domain	K2P (1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 15, 16, 17, 18)

Other


M⁺: TRP cation channel	TRPA (1) · TRPC (1, 2, 3, 4, 4AP, 5, 6, 7) · TRPM (1, 2, 3, 4, 5, 6, 7, 8) · TRPML (1, 2, 3) · TRPP (1, 2) · TRPV (1, 2, 3, 4, 5, 6)

Cl^-: Chloride channel	ANO1 · Bestrophin (1, 2) · CFTR · CLCA (1, 2, 3, 4) · CLCN (1, 2, 3, 4, 5, 6, 7, KA, KB) · CLIC (1, 2, 3, 4, 5, 6, L1) · CLNS (1A, 1B)

Cyclic nucleotide-gated (FC)	α (1, 2, 3, 4) · β (1, 2, 3) · HCN (1, 2, 3, 4)

Porin	Aquaporin (1, 2, 3, 4, 5, 7, 8, 9) · Voltage-dependent anion channel (1, 2, 3) · General bacterial porin family

General	Ligand-gated ion channel · Voltage-gated ion channel · Stretch-activated ion channel

	see also disorders

v • d • e Membrane transport protein: ion pumps

Symporter, Cotransporter	Na+/K+/2Cl- - Na/Pi3 - Na+/Cl- - Na/glucose - Na+/I- - Cl-/K+ (4, 5)

Antiporter (exchanger)	Na+/H+ - Na+/Ca2+ (Na+/(Ca2+-K+)) - Cl-/HCO3- (Band 3) - Cl-formate exchanger - Cl-oxalate exchanger

P-type ATPase	Cu++ - Ca+ (SERCA, PMCA, SPCA) - Na+/K+ - H+/K+ - H+

F- and V-type ATPase	ATP synthase - H+ (F-type) - H+ (V-type)

Other	Halorhodopsin (Cl-) - bacteriorhodopsin (H+)

v • d • e Membrane transport protein: neurotransmitter transporters

Vesicular	Vesicular monoamine (VMAT1, VMAT2) - Vesicular acetylcholine

Other	Glutamate - Monoamine (DAT, NET, SERT, PMAT)

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Membrane transport protein

Contents

Facilitated diffusion

More examples

See also

References

External links