Function and Structure
These proteins localize to two regions of the nuclear compartment, the nuclear lamina -- a proteinaceous structure layer subjacent to the inner surface of the nuclear envelope and throughout the nucleoplasm in the nucleoplasmic "veil".
Comparison of the lamins to cytoskeletal intermediate filaments shows that lamins have an extra 42 residues (six heptads) within coil 1b. The c-terminal tail domain contains a nuclear localization signal (NLS), an Ig-fold-like domain, and in most cases a'][;p carboxy-terminal CaaX box that is isoprenylated and carboxymethylated (lamin C does not have a CAAX box). Lamin A is further processed to remove the last 15 amino acids and its farnesylated cysteine.
Lamin A and lamin C form homodimers which associate head to tail.
During mitosis, lamins are phosphorylated by Mitosis-Promoting Factor (MPF), which drives the disassembly of the lamina and the nuclear envelope. After chromosome segregation, dephosphorylation of nuclear lamins promotes reassembly of the nuclear envelope.
Read more about this topic: Lamin
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