Telophase

By Levi Clancy for Student Reader on
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How is the dismantling of the nuclear lamina during prophase and its reassembly during telophase accomplished? Where does the nuclear envelope go during mitosis? Long and fibrous lamin proteins form a layer of structural support for the nuclear envelope. Lamin is phosphorylated in prometaphase, causing a conformational change and the loss of laminal structural properties. Without laminal support, the nuclear membrane breaks apart and absorbs into the smooth endoplasmic reticulum. The endoplasmic reticulum breaks apart, but is bound to the lamin via the inner nuclear membrane Lamin B Receptor; and the lamin binds to chromatin.

As anaphase ends, dephosphorylation of existing lamin begins. Once the genetic material has fully segregated at the completion of anaphase, production of new lamin is well underway. The new lamin drags tubes of smooth endoplasmic reticulum across the surface of the chromatin; these tubes flatten and merge, forming a solid nuclear membrane. The endoplasmic reticulum and lamin detach themselves from the chromatin. In the mature daughter cell, the lamina is a continous layer that is bound to the inner membrane of the nuclear envelope by emerin proteins.