You study a serine/threonine-protein kinase, which is likely involved in the regulation of actin dynamics. You...

You study a serine/threonine-protein kinase, which is likely involved in the regulation of actin dynamics. You

have good knowledge about the kinase (such as its kinase domain information and which residues are

catalytic sites etc). You found a RhoGEF by yeast two-hybrid screening using the kinase as bait. Further,

through co-immunoprecipitation assay, you confirmed that the kinase specifically interacts with the

RhoGEF. Since RhoGEF is well known to regulate actin oligomerization, you expect that the protein might

provide an important clue about the role of the kinase in the regulation of actin dynamics. How would you

define a signaling pathway from the kinase to actin polymerization via the RhoGEF as a mediator? What

would be your questions to define the pathway, and what experiments would you do to address them?

Expert Solution

The rho-associated kinase is a serine-threonine kinase. That are the downstream effectors of the Rho GTPase. The kinase act as a molecular switch in the regulation of actin polymerization.

All other details mentioned below in the signaling cascade.

When the signal approach the extracellular receptor, downward signaling will happen. Important ligand molecules are epidermal growth factor, platelet-derived growth factor, etc. Ligand receptor binding leads to the activation of RHO GEF which will exchange inactive Rho GDP to active Rho GTP. Now the Rho is active GTP form. The downward signaling is by two ways, by Rho kinase and by formin. Here we will deals with the Rho kinase-mediated actin polymerization. Rho-kinase can phosphorylate its downstream effectors. Myosin light-chain is the downstream effecter so Kinase phosphorylate the myosin-light chain to activate them, so now the myosin II light chain is activated by kinase. Another downstream effector is the myosin light chain phosphatases, phosphorylation by kinase make them inactive. So myosin is active because, no phosphatases are there to inactive or dephosphorylate them. This leads to contraction.

Experiment done to study is that. Introduction of inhibitor of GEF so the actin polymerization inhibited. They repeated experiment with dominant-negative and active mutant small GTP (change GEF ).

If you have got any doubts regarding the answers or the way I describe, or anything else regarding the topic please do inform me in the comment session.

So we can discuss it as an interacting session.
Hope you like it.

Thanks a lot.

gladiator answered 2 years ago

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