title: Structural analysis of the predicted coiled-coil rod domain of the cytoplasmic bullous pemphigoid antigen (BPAG1). Empirical localization of the N-terminal globular domain-rod boundary.
abstract: The bullous pemphigoid antigen BPAG1 is required for keratin filament linkage to the hemidesmosome, an adhesion complex in epithelial basal cells. BPAG1 structural organization is similar to the intermediate filament-associated proteins desmoplakin I (DPI) and plectin. All three proteins have predicted dumbbell-like structure with central alpha-helical coiled-coil rod and regions of N- and C-terminal homology. To characterize the size of the N-terminal globular domain in BPAG1, two polypeptides spanning possible boundaries with the coiled-coil rod domain of BPAG1 were expressed in Escherichia coli. BP-1 (Mr = 111,000), containing amino acids 663-1581 of BPAG1 (Sawamura, D., Li, K., Chu, M.-L., and Uitto, J. (1991) J. Biol. Chem. 266, 17784-17790), and BP-1A, with a 186 amino acid N-terminal deletion, were purified. BP-1 and BP-1A behave as highly asymmetric dimers in aqueous solution according to velocity sedimentation and gel filtration. Both have globular heads with rod-like tails of roughly equal length, 55-60 nm, upon rotary shadowing. BP-1A content of alpha-helix, determined by circular dichroism, is approximately 90%, consistent with alpha-helical coiled-coil formation in the rod-like tails. The estimated rod length, 383 +/- 57 amino acids (0.15 nm/amino acid), implies that globular folding in the BPAG1 N-terminal extends to the end of N-terminal homology with DPI and plectin. These findings support the existence of a common domain structure in the N-terminal regions of the BPAG1/DPI/plectin family.
authors.affiliation: Department of Medical Biochemistry and Genetics, Texas A & M College of Medicine, College Station, Texas 77843, USA.
authors.forename: H Y
authors.initials: HY
authors.lastname: Tang
authors.forename: A F
authors.initials: AF
authors.lastname: Chaffotte
authors.forename: S M
authors.initials: SM
authors.lastname: Thacher
mesh_terms: D000595:Amino Acid Sequence; D001324:Autoantigens / Q000096:biosynthesis / Q000737:chemistry* / Q000648:ultrastructure; D002352:Carrier Proteins; D002942:Circular Dichroism; D003001:Cloning, Molecular; D003094:Collagen; D003598:Cytoskeletal Proteins / Q000737:chemistry; D051180:Desmoplakins; D000071821:Dystonin; D004848:Epithelium / Q000502:physiology; D006801:Humans; D007381:Intermediate Filament Proteins / Q000737:chemistry; D007633:Keratins / Q000502:physiology; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D024041:Non-Fibrillar Collagens; D010391:Pemphigoid, Bullous / Q000276:immunology*; D051190:Plectin; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000648:ultrastructure; D017386:Sequence Homology, Amino Acid; D000097805:Collagen Type XVII
chemical_list: D001324:Autoantigens; D002352:Carrier Proteins; D003094:Collagen; D003598:Cytoskeletal Proteins; D051180:Desmoplakins; D000071821:Dystonin; D007381:Intermediate Filament Proteins; D007633:Keratins; D009419:Nerve Tissue Proteins; D024041:Non-Fibrillar Collagens; D051190:Plectin; D011994:Recombinant Proteins; D000097805:Collagen Type XVII; C495294:DSP protein, human; C486268:DST protein, human; C495332:PLEC protein, human