Proteins
Proteins

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Proteins

5.5 Summary of Section 5

  1. Proteins are dynamic molecular machines. All proteins bind to other molecules, whether ions, small molecules or macromolecules, and these interactions are critical to the protein's function. The activity of proteins is regulated by changes in conformation.

  2. In allosterically regulated proteins, binding of one ligand affects the conformation of a remote part of the protein, thereby regulating interaction with a second ligand. Cooperative binding is a type of allosteric regulation in which conformational changes are communicated between subunits (e.g. in O2 binding in haemoglobin).

  3. A common mechanism for regulating protein conformation and activity is through cycles of phosphorylation (by kinases) and dephosphorylation (by phosphatases).

  4. G proteins are regulated by binding and hydrolysis of GTP. Generally, the GTP-bound form of the protein is active and the GDP-bound form is inactive. Many G proteins require other proteins to enhance their GTPase activity (GAPs) or to accelerate exchange of GDP for GTP (GEFs). Two of the largest families of G proteins are small G proteins (exemplified by Ras) and trimeric G proteins.

  5. Trimeric G proteins contain α, β and γ subunits and the α subunit has the GTP binding site and GTPase activity. These G proteins transduce signals from 7-helix transmembrane receptors.

S377_2

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371