quinta-feira, 7 de maio de 2015

ATP-binding cassette (ABC) family


It is time to learn about one more gene superfamily.

Today, we will briefly introduce ATP-binding cassette (ABC) family, a very important group of proteins in our metabolism.

ATP-binding cassette proteins, or just ABCs, are present in cells from prokaryotes (bacterias) to eukaryotes (including mammals). Most ABCs are transmembrane proteins responsible for the transport of many substrates across cellular membrane, putting chemical compounds in and out the cell. Examples of ABCs substrates vary at length, but include amino acids, peptides, ions and others molecules that are usually hydrophilic (polar).

The transport of substrates carried out by ABCs occurs at an energy cost. ATP molecules must be   hydrolysed, realising the energy used to bind and move the substrate across the membrane. In other words, ABC proteins perform active transport (expend energy). The ABC proteins has an  hydrophilic portion in its structure and also an lipophilic portion, which is embedded inside the cellular membrane.

ABC proteins consist principally in two distinct domains, the transmembrane domain (TMD) and the nucleotide-binding domain (NBD). The first is compound for alpha helix in membrane bilayer. When transport a substrate, the TMD change its conformation and adapts to it. And the NBD is responsible for interact with ATP molecule and make the hydrolysis to produce energy for the protein action.

There are many differents types of ATP-binding cassette, its diversity is big. In the transcriptome we have analysed so far, we found 24 differentes subfamilies of ABC!

More exciting news are about to come.

See you soon!

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