title: Microtubule actin crosslinking factor 1b: a novel plakin that localizes to the Golgi complex.
abstract: MACF1 (microtubule actin crosslinking factor), also called ACF7 (actin crosslinking family 7) is a cytoskeletal linker protein that can associate with both actin filaments and microtubules. We have identified a novel alternatively spliced isoform of MACF1. We named this isoform MACF1b and renamed the original isoform MACF1a. MACF1b is identical to MACF1a, except that it has a region containing plakin (or plectin) repeats in the middle of the molecule. MACF1b is ubiquitously expressed in adult tissues with especially high levels in the lung. We studied the subcellular localization of MACF1b proteins in mammalian cell lines. In two lung cell lines, MACF1b was chiefly localized to the Golgi complex. Upon treatments that disrupt the Golgi complex, MACF1b redistributed into the cytosol, but remained co-localized with the dispersed Golgi ministacks. MACF1b proteins can be detected in the enriched Golgi fraction by western blotting. The domain of MACF1b that targets it to the Golgi was found at the N-terminal part of the region that contains the plakin repeats. Reducing the level of MACF1 proteins by small-interfering RNA resulted in the dispersal of the Golgi complex.
authors.affiliation: Department of Pathology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
authors.forename: Chung-Ming
authors.initials: CM
authors.lastname: Lin
authors.forename: Hui-Jye
authors.initials: HJ
authors.lastname: Chen
authors.forename: Conrad L
authors.initials: CL
authors.lastname: Leung
authors.forename: David A D
authors.initials: DA
authors.lastname: Parry
authors.forename: Ronald K H
authors.initials: RK
authors.lastname: Liem
mesh_terms: D000818:Animals; D019556:COS Cells; D002451:Cell Compartmentation / Q000502:physiology; D002522:Chlorocebus aethiops; D015536:Down-Regulation / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism / Q000648:ultrastructure; D005786:Gene Expression Regulation / Q000502:physiology; D006056:Golgi Apparatus / Q000378:metabolism*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008168:Lung / Q000378:metabolism / Q000648:ultrastructure; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D051179:Plakins / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D034741:RNA, Small Interfering
chemical_list: C490632:Macf1 protein, mouse; D008840:Microfilament Proteins; D051179:Plakins; D020033:Protein Isoforms; D034741:RNA, Small Interfering