| Lamins are type V intermediate filament proteins and are grouped into constitutively expressed B-type lamins and developmentally regulated A-type lamins. Lamin-binding proteins in the nuclear lamina and the nuclear interior include several protein families and/or types of proteins in higher eukaryotes such as the inner nuclear membrane proteins, lamin B receptor, emerin, MANI, three isoforms of lamina-associated polypeptide 1 (LAP 1), and several isoforms of LAP 2. Up to six LAP 2 isoforms derive from a single gene by alternative splicing in mammals and various isoforms have been described in Xenopus. The best characterized LAP2 isoforms are the inner nuclear membrane protein LAP 2 beta and the nucleoplasmic protein LAP 2 alpha, which are identical in their N-terminal 187-amino acid constant region but differ in their C termini. LAP 2 alpha specifically interacts with A-type lamins within the nuclear interior as part of a detergent- and salt-resistant nucleoskeletal structure. |
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