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. 2009 Jul 1;119(7):1825–1836. doi: 10.1172/JCI37679

Figure 1. The nuclear lamina.

Figure 1

(A) The nuclear lamina is a meshwork of IFs localized primarily to the nucleoplasmic face of the inner nuclear membrane (shown schematically in red). The lamins interact with several integral proteins of the inner nuclear membrane, including lamin B receptor (LBR), MAN1 (encoded by the LEMD3 gene), emerin, lamina-associated polypeptide 1 (LAP), LAP2β, small nesprin 1 isoforms, and SUNs. SUNs interact with large nesprin 2 isoforms, integral proteins of the outer nuclear membrane, which also interact with actin, linking the nuclear lamina to the cytoskeleton. (B) In humans, 3 genes encode nuclear lamins. LMNA on chromosome 1q21.2 encodes the A-type lamins, with prelamin A and lamin C generated by alternative RNA splicing being the major somatic cell isoforms. Prelamin A has 98 unique amino acids and lamin C 6 unique amino acids at their carboxyl terminus (gray striping). LMNB1 on chromosome 5q23.3–q31.1 encodes lamin B1, and LMNB2 on chromosome 19p13.3 encodes lamin B2, the somatic cell B-type lamins. All the lamins have conserved α-helical rod domains and variable head and tail domains preceding and following the central rod domain. The nuclear localization signals are located in the tail domain (indicated in red). Prelamin A, lamin B1, and lamin B2 have carboxyl-terminal CaaX motifs, a signal for protein farnesylation.