Lamins are components of the nuclear lamina, a fibrous layer on the nucleoplasmic side of the inner nuclear membrane, which is thought to provide a framework for the nuclear envelope and may also interact with chromatin. Lamin A and C are present in equal amounts in the lamina of mammals. Recruited by DNA repair proteins XRCC4 and IFFO1 to the DNA double-strand breaks (DSBs) to prevent chromosome translocation by immobilizing broken DNA ends (By similarity). Plays an important role in nuclear assembly, chromatin organization, nuclear membrane and telomere dynamics. Required for normal development of peripheral nervous system and skeletal muscle and for muscle satellite cell proliferation. Required for osteoblastogenesis and bone formation. Also prevents fat infiltration of muscle and bone marrow, helping to maintain the volume and strength of skeletal muscle and bone. Required for cardiac homeostasis. Prelamin-A/C can accelerate smooth muscle cell senescence. It acts to disrupt mitosis and induce DNA damage in vascular smooth muscle cells (VSMCs), leading to mitotic failure, genomic instability, and premature senescence (By similarity). Homodimer of lamin A and lamin C. Interacts with lamin-associated polypeptides IA, IB and TMPO-alpha, RB1 and with emerin. Interacts with SREBF1, SREBF2, SUN1, SUN2 and TMEM43. Interacts with TMEM201. Proteolytically processed isoform A interacts with NARF. Prelamin-A/C interacts with EMD. Interacts with MLIP. Interacts with DMPK; may regulate nuclear envelope stability. Interacts with SUV39H1; the interaction increases stability of SUV39H1 (By similarity). Interacts with ITSN1 isoform 2 (By similarity). Interacts with IFFO1; the interaction forms an interior nucleoskeleton and the recruitment to DNA double-strand breaks (By similarity). Interacts (via C-terminus) with LEMD2 (via N-terminus) (in vitro). Farnesylation of prelamin-A/C facilitates nuclear envelope targeting and subsequent cleavage by ZMPSTE24/FACE1 to remove the farnesyl group produces mature lamin-A/C, which can then be inserted into the nuclear lamina. EMD is required for proper localization of non-farnesylated prelamin-A/C (By similarity). Phosphorylation status of S-22 determines its localization between double-strand break (DSB) sites and the nuclear matrix (By similarity). Isoform A and isoform C are present in equal amounts in the lamina of mammals. Proteolytic cleavage of the C-terminal of 18 residues of prelamin-A/C results in the production of lamin-A/C. The prelamin-A/C maturation pathway includes farnesylation of CAAX motif, ZMPSTE24/FACE1 mediated cleavage of the last three amino acids, methylation of the C-terminal cysteine and endoproteolytic removal of the last 15 C-terminal amino acids. Proteolytic cleavage requires prior farnesylation and methylation, and absence of these blocks cleavage (By similarity). Sumoylation is necessary for the localization to the nuclear envelope. Farnesylation of prelamin-A/C facilitates nuclear envelope targeting. Increased phosphorylation of the lamins occurs before envelope disintegration and probably plays a role in regulating lamin associations. Phosphorylation status of S-22 determines its localization between double-strand break (DSB) sites and the nuclear matrix (By similarity). The structural integrity of the lamina is strictly controlled by the cell cycle, as seen by the disintegration and formation of the nuclear envelope in prophase and telophase, respectively. Belongs to the intermediate filament family.