Precursor sequence, processing, and urothelium-specific expression of a major 15-kDa protein subunit of asymmetric unit membrane
| Autor: | J H, Lin, X R, Wu, G, Kreibich, T T, Sun |
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| Rok vydání: | 1994 |
| Předmět: |
Macromolecular Substances
Protein Conformation Molecular Sequence Data Restriction Mapping Urinary Bladder Gene Expression Cell Fractionation Transfection Polymerase Chain Reaction Epithelium Protein Structure Secondary Cell Line Species Specificity Microsomes Centrifugation Density Gradient Animals Humans Trypsin Amino Acid Sequence Cyanogen Bromide RNA Messenger DNA Primers Gene Library Mammals Base Sequence Cell Membrane Membrane Proteins Cell Differentiation Epithelial Cells DNA Peptide Fragments Molecular Weight Blotting Southern Protein Biosynthesis Uroplakin II RNA Cattle Poly A Protein Processing Post-Translational |
| Zdroj: | The Journal of biological chemistry. 269(3) |
| ISSN: | 0021-9258 |
| Popis: | The asymmetric unit membrane (AUM) is a highly specialized biomembrane elaborated by terminally differentiated urothelial cells. It contains quasi-crystalline arrays of 12-nm protein particles each of which is composed of six dumbbell-shaped subdomains. In this paper we describe the precursor sequence, processing and in vitro membrane insertion properties of bovine uroplakin II (UPII), a 15-kDa major protein component of AUM. The cDNA-deduced amino acid sequence revealed that UPII is synthesized as a precursor protein containing a cleavable signal peptide of approximately 26 amino acids, a long pro-sequence of approximately 59 residues harboring three potential N-glycosylation sites, and the mature polypeptide of 100 residues. In vitro translation of UPII mRNA demonstrated that UPII is indeed first synthesized as a 19-kDa precursor, which loses its signal peptide upon insertion into added microsomes; this process is accompanied by the acquisition of high mannose-type oligosaccharides giving rise to a 28-kDa precursor which is completely protected from the digestion by exogenous proteases. These results, together with the presence of a stretch of 25 hydrophobic amino acids at the C terminus, suggest that UPII protein is anchored to the lipid bilayer via its C-terminal membrane-spanning domain with its major N-terminal domain exposed luminally. The formation of the 15-kDa mature UPII requires the removal of the pro-sequence by a furin-like endoprotease. Since only mature UPII devoid of this pro-sequence can interact with 27-kDa uroplakin I, the proteolytic processing of UPII precursor may play an important role in regulating the assembly of AUM. Finally, we showed that genomic sequences cross-hybridizing with bovine UPII cDNA are present in many mammals suggesting that UPII performs a highly conserved function in the terminally differentiated cells of mammalian urinary bladder epithelium. |
| Databáze: | OpenAIRE |
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