biology

Organic cation transport protein

Organic cation transport protein is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Organic cation transport protein rather than just read about it. In short: An organic cation transport protein mediates the transport of organic cations across the cell membrane. These proteins are members of the solute carrier family, subfamily 22.

Key takeaways

Organic cation transport protein belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Organic cation transport protein to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Organic cation transport protein from memory before moving on to harder problems.

Reference excerpt

An organic cation transport protein mediates the transport of organic cations across the cell membrane. These proteins are members of the solute carrier family, subfamily 22. This family of proteins can also transport zwitterions and anions, though it is a different subfamily of solute carrier proteins than the organic anion transporters.

Function Organic cation transport proteins (OCTs) are involved in membrane transport through facilitated diffusion of organic cations and some weak bases. They are crucial for the disposal of many organic cations that come from drugs or other environmental sources. They also allow for the recycling of necessary organic cations. Some of these organic cation transport proteins are compound-specific, and others transport a broad range of cations across the membrane. For example, the disposing of the blood sugar medication Metformin is dependent on organic cation transport proteins[1].

Structure The general structure of an OCT or OCTN consists of 11-12 alpha-helical transmembrane protein domains. These create a transmembrane unit that creates loops on both sides of the membrane. There is typically a large extracellular loop with glycosylation sites at the beginning of the transporter, followed by many smaller loops that connect the transmembrane protein domains on the extracellular side. The loops found on the inside of the cell contain many sites for phosphorylation[2]. There is also an intracellular loop between the transmembrane domains 6 and 7 that contains phosphorylation sites that are believed to contribute to regulation of activity of the organic cation transport protein. Some of these phosphorylation sites are shared between the different organic cation transport proteins[3].

Nomenclature The various types of organic cation transport proteins are often referred to in its respective abbreviated form or by the gene that codes it. For example, OCT1 is coded by the SLC22A1 gene. Similarly, OCT2 is often called SLC22A2.

Proteins

References Koepsell, H., Endou, H. The SLC22 drug transporter family. Pflugers Arch - Eur J Physiol 447, 666–676 (2004). https://doi-org.byu.idm.oclc.org/10.1007/s00424-003-1089-9 Ciarimboli, G., Schlatter, E. Regulation of organic cation transport. Pflugers Arch - Eur J Physiol 449, 423–441 (2005). https://doi-org.byu.idm.oclc.org/10.1007/s00424-004-1355-5 Kerb, R., Brinkmann, U., Chatskaia, N., Gorbunov, D., Gorboulev, V., Mornhinweg, E., Keil, A., Eichelbaum, M. & Koepsell, H. (2002). Identification of genetic variations of the human organic cation transporter hOCT1 and their functional consequences. Pharmacogenetics, 12 (8), 591-595.

Worked examples

Example 1 — a first encounter with Organic cation transport protein

Start with the simplest possible case. Write down what Organic cation transport protein claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Organic cation transport protein before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Organic cation transport protein ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Organic cation transport protein

In research: Organic cation transport protein appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Organic cation transport protein in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Organic cation transport protein is common in secondary-school and first-year university syllabi. It links to neighbouring topics Solute carrier family, Transmembrane transporters, Transport proteins, so understanding it makes those chapters shorter.
In everyday life: Look for Organic cation transport protein outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Organic cation transport protein in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Organic cation transport protein means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
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Frequently asked questions

What is Organic cation transport protein in simple terms?

An organic cation transport protein mediates the transport of organic cations across the cell membrane. These proteins are members of the solute carrier family, subfamily 22.

Why does Organic cation transport protein matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Organic cation transport protein?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Organic cation transport protein.