Porin

Porin is a type of protein found in the outer membrane of Gram-negative bacteria. They form channels that allow the passive diffusion of small molecules across the membrane.

Structure

Porins are typically composed of beta barrel structures that span the outer membrane. The barrel is formed by the arrangement of beta sheets into a cylindrical shape. The interior of the barrel forms the channel through which molecules can pass.

Function

The primary function of porins is to facilitate the transport of small molecules across the outer membrane of Gram-negative bacteria. This includes nutrients needed for the bacteria's survival, as well as waste products that need to be expelled. Some porins are specific for certain types of molecules, while others are more general in their function.

Types

There are several types of porins, including general porins, specific porins, and regulated porins. General porins allow a wide range of molecules to pass through, while specific porins only allow certain types of molecules. Regulated porins can open or close in response to certain signals.

Clinical significance

Porins are of clinical significance because they can contribute to the antibiotic resistance of Gram-negative bacteria. Some antibiotics can enter bacteria through porins, but changes in the porins can prevent this, making the bacteria resistant to the antibiotic.

See also

• Outer membrane
• Gram-negative bacteria
• Antibiotic resistance

References

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