What is the Difference Between ABC and SLC Transporters

The key difference between ABC and SLC transporters is that ABC transporters are carrier proteins assisting in the movement of substances across a biological membrane through primary active transport mechanism, while SLC transporters are carrier proteins assisting in the movement of substances across a biological membrane through secondary active transport and facilitative diffusion mechanisms.

Transporters or membrane transport/carrier proteins are highly specialized membrane-spanning proteins involved in the movement of ions, peptides, small molecules, lipids, and macromolecules across the biological membrane. These transporters use both active and passive transport mechanisms. Passive transport mechanisms are diffusion and facilitated transport. Active transport mechanisms are primary active transport and secondary active transport. They are classified into three classes: ABC transporters, P-type ATPases, and SLC transporters.

CONTENTS

1. Overview and Key Difference
2. What are ABC Transporters
3. What are SLC Transporters
4. Similarities – ABC and SLC Transporters
5. ABC vs SLC Transporters in Tabular Form
6. Summary – ABC vs SLC Transporters

What are ABC Transporters?

ABC transporters (ATP binding cassette transporter) are carrier proteins that assist in the movement of substances across a biological membrane through a primary active transport mechanism. They transport a wide range of substances, mainly to the outside of a cell membrane or organelle. The substances that they transport include lipids and sterols, ions, small molecules, drugs, and large polypeptides. Moreover, ABC transporters, specifically in prokaryotes, can also uptake certain substances such as a large variety of nutrients, biosynthetic precursors, trace metals, and vitamins. ABC transporters play a very critical role in the development of multi-drug resistance in cancer cells. This is because the overexpression of ABC transporters can result in pumping out of chemotherapeutic drugs outside the cell faster than they can enter the cell. This can also develop resistance to antibiotics.

They are a transport system superfamily. ABC transporters are encoded by one of the largest and oldest gene families. ABC transporters have multiple subunits. One or two of these are transmembrane proteins, and one or two are membrane-associated AAA ATPases. The ATPase subunit uses the energy of ATP to translocate substances across the membrane. Furthermore, hundreds of ABC transporters have been characterized by both prokaryotes and eukaryotes.

What are SLC Transporters?

SLC (solute carrier family) transporters are carrier proteins that assist in the movement of substances across a biological membrane through secondary active transport and facilitative diffusion mechanisms. They are normally located on the cell membrane as well as on the intracellular membrane of organelles. SLC transporters are membrane transport proteins that include over 400 members, which are organized into 66 families.

Moreover, the solutes that are transported by these proteins include both charged and uncharged organic molecules, inorganic ions, and gas ammonia. Furthermore, ASLC susceptibility loci have been strongly associated with metabolic diseases and other diseases, including insulin resistance, type 2 diabetes mellitus, elevated blood pressure, chronic kidney disease, gout, asthma, inflammatory bowel disease, cancer, dementia, epilepsy, Parkinson’s disease, and anxiety disorders. Examples of the solute carrier family are biogenic amine transporters (NET, DAT, and SERT) and the Na⁺/H⁺ exchanger.

What are the Similarities Between ABC and SLC Transporters?

• ABC and SLC transporters are two different types of carrier proteins assisting in the movement of substances across a biological membrane.
• They are membrane proteins.
• Both are transport system superfamilies.
• They can transport substances through an active transport mechanism.
• When dysfunctional, both transporters can cause diseases.

What is the Difference Between ABC and SLC Transporters?

ABC transporters are carrier proteins that assist in the movement of substances across a biological membrane through a primary active transport mechanism, while SLC transporters are carrier proteins that assist in the movement of substances across a biological membrane through secondary active transport and facilitative diffusion mechanisms. Thus, this is the key difference between ABC and SLC transporters. Furthermore, ABC transporters belong to a superfamily that has 49 members organized into 7 families, while SLC transporters belong to a superfamily that has 400 members organized into 66 families.

The below infographic presents the differences between ABC and SLC transporters in tabular form for side by side comparison.

Summary – ABC vs SLC Transporters

ABC and SLC transporters are two different types of carrier proteins. They are membrane proteins assisting in the movement of substances across a biological membrane. Both belong to protein superfamilies. ABC transporters assist in the movement of substances across a biological membrane through a primary active transport mechanism, while SLC transporters assist in the movement of substances across a biological membrane through secondary active transport and facilitative diffusion mechanisms. So, this is the key difference between ABC and SLC transporters.

Reference:

1. “Solute Carrier Protein.” An Overview | ScienceDirect Topics.
2. “ABC Transporter.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “1l7v opm” By Andrei Lomize – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Fncel-08-00161-g0001” By Annalisa Scimemi – (CC BY 2.0) via Commons Wikimedia