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LEM (Lap2/Emerin/Man1) domain found in emerin, lamina-associated polypeptide 2 (LAP2), inner nuclear membrane protein Man1 and similar proteins The family corresponds to a group of inner nuclear membrane proteins containing LEM domain. Emerin occurs in four phosphorylated forms and plays a role in cell cycle-dependent events. It is absent from the inner nuclear membrane in most patients with X-linked muscular dystrophy. Emerin interacts with A-type and B-type lamins. Man1, also termed LEM domain-containing protein 3 (LEMD3) is an integral protein of the inner nuclear membrane that binds to nuclear lamins and emerin, thus playing a role in nuclear organization. LAP2, also termed thymopoietin (TP), or thymopoietin-related peptide (TPRP), is composed of isoform alpha and isoforms beta/gamma and may be involved in chromatin organization and post-mitotic reassembly. Some LAP2 isoforms are inner nuclear membrane proteins that can bind to nuclear lamins and chromatin, while others are non-membrane nuclear polypeptides. This family also contains LEM domain-containing protein LEMP-1 and LEM2. LEMP-1, also termed cancer/testis antigen 50 (CT50), is encoded by LEMD1, a novel testis-specific gene expressed in colorectal cancers. LEMP-1 may function as a cancer-testis antigen for immunotherapy of colorectal carcinoma (CRC). LEM2, also termed LEMD2, is a novel Man1-related ubiquitously expressed inner nuclear membrane protein required for normal nuclear envelope morphology. Association with lamin A is required for its proper nuclear envelope localization while its binding to lamin C plays an important role in the organization of lamin A/C complexes. Some uncharacterized LEM domain-containing proteins are also included in this family. Unlike other family members, these harbor an ankyrin repeat region that may mediate protein-protein interactions. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",