Inner nuclear membrane proteins: functions and targeting.
We summarize the properties of integral membrane proteins that reside in the inner nuclear membrane, including lamin B receptor (LBR), lamina-associated polypeptide (LAP) 1, LAP2, emerin, MAN1 and nurim. Most of these proteins interact with lamins and chromatin. Some data also suggest more speculative functions such as gene regulation and possibly sterol metabolism. Mutations in emerin and nuclear lamins have been associated with muscular dystrophies and lipodystrophy, raising new questions about the functions of inner nuclear membrane proteins. Integral proteins of the inner nuclear membrane are synthesized on the rough endoplasmic reticulum (ER) and reach the inner nuclear membrane by lateral diffusion in the connected ER and nuclear envelope membranes. Associations with nuclear ligands retain them in the inner nuclear membrane. Further investigation of the functions and targeting of inner nuclear membrane proteins are needed to determine how they are involved in human disease.
Holmer
L
L
Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Worman
H J
HJ
D000818:Animals; D002843:Chromatin / Q000378:metabolism; D006801:Humans; D034921:Lamin Type B; D034882:Lamins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D020389:Muscular Dystrophy, Emery-Dreifuss / Q000503:physiopathology; D009685:Nuclear Envelope / Q000737:chemistry / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D013946:Thymopoietins / Q000235:genetics / Q000378:metabolism
D002843:Chromatin; D034921:Lamin Type B; D034882:Lamins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; D013946:Thymopoietins; C092710:emerin