The activity of the MAPs is regulated by the reversible phosphorylation of their projection domains.

TLS Online TPP Program

#Id: 7769

#Unit 2. Cellular Organization

Nuclear envelope

Double-membrane structure; the outer membrane is continuous with the endoplasmic reticulum and the two membranes are perforated by nuclear pore complexes

TLS Online TPP Program

#Id: 7770

#Unit 2. Cellular Organization

The inner nuclear membrane contains proteins that act as binding sites for chromosomes and for the nuclear lamina.

TLS Online TPP Program

#Id: 7771

#Unit 2. Cellular Organization

Nuclear lamina

Fibrous network on the inner surface of the nuclear envelope composed of lamin intermediate filaments that provides structural support for the nuclear envelope and also acts as an anchoring site for chromosomes.

TLS Online TPP Program

#Id: 7772

#Unit 2. Cellular Organization

The inner membrane is surrounded by the outer nuclear membrane, which is continuous with the membrane of the ER. The outer nuclear membrane is studded with ribosomes engaged in protein synthesis.

TLS Online TPP Program

#Id: 7773

#Unit 2. Cellular Organization

Transport of proteins from the cytoplasm into the nucleus and movement of macromolecules, including mRNAs, tRNAs, and ribosomal subunits, out of the nucleus occurs through nuclear pores, which span both membranes of the nuclear envelope.

TLS Online TPP Program

#Id: 7774

#Unit 2. Cellular Organization

Each nuclear pore is formed from an elaborate structure termed the nuclear pore complex (NPC), which is one of the largest discrete protein assemblages in the cell.