You are interested in understanding the regulation of nuclear lamina assembly

Question

To create an in vitro system for studying this process you start with partly purified nuclear lamina subunits to which you will add back purified cellular components to drive nuclear lamina assembly. Before you start doing experiments, your instructor suggests that you consider what type of conditions would be most amenable to the assembly of the nuclear lamina from its individual subunits in vitro. Which of the following conditions do you predict would be most likely to enhance the assembly of the nuclear lamina?
(a) addition of phosphatase inhibitors
(b) addition of ATP
(c) addition of a concentrated salt solution that is 10 times the concentration normally found in the nucleoplasm
(d) addition of protein kinase inhibitors

Answer 1

(d) The phosphorylation of nuclear lamins by protein kinases induces conformational changes that weaken the binding between nuclear lamin tetramers; thus, inhibiting protein kinases may enhance assembly of the nuclear lamina. Adding phosphatase inhibitors [choice (a)] or ATP [choice (b)] will enhance the activity of any co-purifying protein kinases and enhance disassembly. Because noncovalent protein–protein interactions hold the nuclear lamina together, the addition of a very concentrated salt solution will inhibit proper nuclear lamina assembly [choice (c)].