Which proteins primarily compose the nuclear lamina?

• A. Lamins
• B. Actin
• C. Tubulin
• D. Keratins

Answer: (C)

The key idea is that the nuclear lamina is a fibrous network just under the inner nuclear membrane that gives the nucleus its structure and organization. This lattice is built mainly from lamins, which are type V intermediate filament proteins. They polymerize to form the supportive meshwork that maintains nuclear shape, helps organize chromatin, and interacts with nuclear pore complexes. Because lamins are specialized to line the nuclear envelope, they are the primary components of the nuclear lamina.

In contrast, actin forms cytoplasmic microfilaments involved in cell movement and shape; tubulin forms microtubules that organize chromosomes and intracellular transport; and keratins are cytoplasmic intermediate filaments found mainly in epithelial cells. None of these constitute the nuclear lamina’s core, which is defined by lamins.