Classification of Membrane Transport Proteins

Continued from properties of families 4-9

Classification of Transport Proteins According to Substrate Specificity

1. Channel Proteins (excluding porins)


I.A. Nonselective
I.B. Water
I.C. Cations
I.D Anions
II.A. Sugars and polyols
II.B. Monocarboxylates
III.B. Amines, amides, and polyamines
VII.B. Proteins

I.A. Nonselective

SubstrateTC numberFamilyDistributionaRegulation
Nonselective 1.A.17CSC Pl
1.A.24Connexin An
1.A.25Innexin An
1E.1-1.E.19Holin B, phage
1.C all toxin-type
poreforming proteins/peptides
B, A, E
1.A.31Annexin E
1.D.5Alamethicin E
1.D.7Beticolin Fu
1.D.8Saponin Pl
Nonselective (slight
cation-over-anion selectivity)
1.A.22MscL Bmechanosensitive (osmotic pressure)
Nonselective (slight
anion-over-cation selectivity)
1.A.23MscS Bmechanosensitive (osmotic pressure)

I.B. Water

Water 1.A.8MIP aquaporinsB, Ehormonal regulation in An
1.A.44UT An

I.C. Cations

Cation-selective 1.A.1.11VIC An voltage-sensitive
1.A.3.1RIR-CaCAn ryanodine-sensitive
1.A.3.2ROR-CaAn inositol-trisphosphate-sensitive
1.A.4TRP-CCAn responsive to pain, heat, etc.
1.A.5PCC An Ca2+-activated
1.A.6.1.2EnaC proton-gated
1.A.6.2.1EnaC An
1.A.7ACC An exogenous-ATP-sensitive
1.A.9.1LIC An acetylcholine-activated
1.A.9.2LIC An serotonin- activated
1.A.10.1.3GIC An glutamate-sensitive
1.A.14NSCC1 An
1.A.15NSCC2 Fu, An
1.A.16Mid1 Y stretch-activated
1.A.26SAT Pl
1.C.58Microcin E492 B
1.D.1Gramicidin AB
1.D.2Syringomycin B
1.D.3Syringopeptin B
1.D.4Tolaasin B
H+1.A.19IVC An, V
1.A.20CybB An, Plarachidonate
1.A.30.1Mot B
1.A.45Mot B
K+1.A.1.1-9VIC B, A, Evoltage-sensitive; Ca2+-activated;
1.A.2IRK-CAn ATP-regulated; G-protein-regulated;
Na+ 1.A.1.10VIC An voltage-sensitive
1.A.6.1.1ENaC An ligand-regulated
1.A.6.3.1EnaC An peptide-regulated
1.A.30.1Mot B
Na+, K+, (Ca2+) selective1.A.10GIC An glutamate-gated
NH4+1.A.26SAT Pl
Heavy-metal ions1.A.35Amoebapore B

I.D Anions

Cl-1.A.9.3LIC An glycine-inhibited
1.A.9.4LIC An glutamate-inhibited
1.A.9.5LIC An g-aminobutyrate-inhibited
1.A.12O-ClCAn voltage-regulated
1.A.13E-ClCAn; B?Ca2+-calmodulin-
Cl- (anion-selective)1.A.11 ClC B, A, Evoltage-regulated
1.A.16Tic110 Pl
1.A.27PLM An hyperpolarization-activated
1.A.36ICC E

II.A. Sugars and polyols

Glycerol 1.A.8MIP-glycerolB, Eglycerol-inducible in bacteria
1,2-Propanediol 1.A.8MIP-glycerolB, Eglycerol-inducible in bacteria

II.B. Monocarboxylates

Organic anions1.A.27PLM An hyperpolarization-activated
Gluconate 1.A.27PLM An hyperpolarization-activated
Glutamate 1.A.27PLM An hyperpolarization-activated
Isethionate 1.A.27PLM An hyperpolarization-activated
Lactate 1.A.27PLM An hyperpolarization-activated
Taurine 1.A.27PLM An hyperpolarization-activated

III.B. Amines, amides, and polyamines

Methylammonium 1.A.26SAT Pl
Urea 1.A.8MIP B
1.A.28UT An
Urea, amides1.A.29UACAn

VII.B. Proteins

Endolysin 1.E.1-1.E.17Holin B, phages
Botulinum toxin, L-chainb1.C.8.1.1BTT B
Cytochrome c1.A.21Bcl-2An
Diphtheria toxin, A-chainb1.C.7.1.1DT B
Nucleases 1.A.34.3Holin B
Proteins 1.A.18Tic110 Pl
1.A.33Hsp70 A, B, E
RNA 1.A.34EVE1-Cviruses
Tetanus toxin, L-chainb1.C.8.1.2BTT B
Thioredoxin 1.A.22.1.1MscL Bosmotic downshift

a Abbreviations used for types of organisms, organelles and viruses are as follows: B, Bacteria; A, Archaea; E, Eucarya; G-, Gram-negative bacteria; G+, Gram-positive bacteria; Y, yeasts; Fu, fungi; Pr, protozoans; Pl, plants; An, animals; Mito, mitochondria; Chloro, chloroplasts; ER, endoplasmic reticulum; Bp, bacteriophage; V, virus

b These toxins in TC category 1.C function to import proteins into the host cell.

Continued with Class 2
Return to Membrane Transport Proteins home page
Return to Biochemical Nomenclature home page