Table 1.

The basic characteristics of the lamins

Lamin type	Genes (in mammalsa)	Major isoforms/(minor isoforms)	Processing of the C-terminus	Isoelectric point (pK) and solubility in mitosis	Expression
A-type lamin	LMNA	Lamin A	Lamin A and AΔ10 have a CaaX motif that is farnesylated and ultimately cleaved with an additional 15 residues from the C-terminus	pK neutral	Lamins A and C are expressed in most somatic differentiated cells Lamin C2 is expressed in germ cells
		Lamin C	Lamin C and C2 have no CaaX motif	Soluble during mitosis
		(Lamin AΔ10 Lamin C2)
B-type lamin	LMNB1	Lamin B1	B-type lamins have a CaaX motif that is farnesylated and carboxymethylated on the cysteine, whereas the (aaX) part of the motif is removed	pK acidic	Lamins B1 and B2 are expressed in most or all somatic cells, but lamin B1 is notably absent from muscle cells. Lamin B3 is found in germ cells
	LMNB2	Lamin B2	The farnesyl group is essential but not sufficient for the peripheral localization of B-type lamins	Membrane-bound in mitosis
		(Lamin B3)

^aThe worm Caenorhabditis elegans has a single lamin gene (lmn-1) encoding a protein that has features of both A-type and B-type lamins