You have joined a lab for your Bio199 research that studies

You have joined a lab for your Bio199 research that studies nuclear envelope breakdown (NEB) . Your project focuses on understanding if phophorylation of laminA is important for NEB. You therefore generate mutant forms of lamin A that cannot be phosphorylated and express these in cells. Expression of wt lamin A serves as a control. You then analyze your cells by immunofluorescence microscopy with antibodies to lamin A to monitor the nuclear envelope and the DNA dye Hoechst to observe DNA condensation

Which of the following statements best explains your result?

LaminA phosphorylation is not important for NEB

LaminA phosphorylation is necessary for DNA condensation

LaminA phosphorylation helps with the assembly of the nuclear envelope

LaminA phosphorylation is necessary for NEB

LaminA phosphorylation induces laminA degradation

(a) Interphase (b) Prophase (c) Metaphase DNA stain DNA stain Lamin A stain Lamin A stain Cells with wild-type human lamin A Cells with mutant human lamin A

Solution

answer=

Lamin A phosphorylation helps with the assembly of the nuclear envelope

Explaination=

nuclear envelope is most dynamic structure & lamin A important for assembly of nuclear envelope

if there is mutation the nuclear envelope completely disassemple

Key feature of this process is hyperphosphorylation of major stuctural proteins of envelope i.e. Lamin A

Lamin A contains Ser 22 & Ser 392 residues

mutation in these residues blocks the disassembly of nuclear lamina & prenent phosphorylation