What causes tropomyosin's affinity for actin?

Question

I'm doing research via expansion microscopy on tropomyosin stability and how it effects actin myosin binding and muscle contraction. I'm super new to research so I don't think my professor expects much from my presentation seeing as how I'm an undergraduate student taking a graduate course but I really want to include in my presentation what causes Tropomyosin to bind to actin in the first place.

 

ANY insight in layman's terms would be so greatly appreciated.

 

Thank you!

Answer 1

Hi, Raegan... for a more detailed look (a VERY detailed look) take a look at this paper:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3037710/

Figure 1 has a picture of actual interactions between the two. If you think about it, ALL interactions between molecules are going to be implementations of the small repertoire of things that 'go together'--positive charges with negative charges; hydrogen bond donors with acceptors, and neutral ('hydrophobic') surfaces matching up to free up waters. The 20 amino acids represent a collection of different options; as you'll see in the paper, different ones can be paired to create interactions that 'reward' proteins when they come together in certain ways.

Answer 2

In layman terms, it involves conformational changes (that is geometrical shapes in 3-D) to where the tropomyosin and the actin align so they can interact/bind.  Calcium plays a key role and the actual mechanism is rather complex.  But if you just want a layman's description, it is sort of like a lock and key.  They line up in such a manner that one can fit into (bind) to the other.