This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Membrane protein

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Membrane proteins constitutes about half of the mass of the plasma membrane. They are often very complex polypeptides which have two essential positions:

  • loosely attached to one or other side of the plasma membrane
  • traversing the membrane as alpha-helical structures:
    • termed integral proteins
    • may pass once across membrane or loop back several times e.g. neurotransmitter receptors
    • hydrophobic amino acids interact with the hydrophobic centre of the membrane
    • tend to be very mobile and this may contribute to function

The functions of plasma membrane proteins include:

  • receptors for extracellular signals e.g. hormones, antibodies, endocytotic vesicles; carbohydrate residues aid this function
  • transduction of extracellular signal: binding of a specific molecule results in a change of configuration of the protein such that its internal structure is changed; thus, secondary messenger formation is triggered internally
  • active pumps: use energy to remove certain ions or molecules e.g. Na-K ATPase
  • passive exchangers: swap molecules between intracellular and extracellular environments
  • channels, e.g. gap junctions
  • site for enzymes
  • structural proteins: tight junction, desmosomes; permit the specialization of individual membrane regions e.g. the difference between apical and basal sides of a small intestinal epithelial cell

Create an account to add page annotations

Annotations allow you to add information to this page that would be handy to have on hand during a consultation. E.g. a website or number. This information will always show when you visit this page.

The content herein is provided for informational purposes and does not replace the need to apply professional clinical judgement when diagnosing or treating any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions.

Connect

Copyright 2024 Oxbridge Solutions Limited, a subsidiary of OmniaMed Communications Limited. All rights reserved. Any distribution or duplication of the information contained herein is strictly prohibited. Oxbridge Solutions receives funding from advertising but maintains editorial independence.