The apical surfaces of urothelial cells are almost entirely covered with plaques consisting of crystalline, hexagonal arrays of 16nm uroplakin particles. Although all four uroplakins, when SDS-denatured, can be digested by chymotrypsin, most uroplakin domains in native urothelial plaques are resistant to the enzyme, suggesting a tightly packed structure. The only exception is the C-terminal, cytoplasmic tail of UPIII (UPIII) which is highly susceptible to proteolysis, suggesting a loose configuration. When uroplakins are solubilized with 2% octylglucoside and fractionated with ion exchangers, UPIa and UPII were bound as a complex by a cation exchanger, whereas UPIb and UPIII were bound by an anion exchanger. This result is consistent with the fact that UPIa and UPIb are cross-linked to UPII and UPIII, respectively, and suggests that the four uroplakins form two pairs consisting of UPIa/II and UPIb/III. Immunogold labelling using a new mouse monoclonal antibody, AU1, revealed that UPIII is present in all urothelial plaques, indicating that the two uroplakin pairs are not segregated into two different types of urothelial plaque and that all plaques must have a similar uroplakin composition. Taken together, these results indicate that uroplakins form a tightly packed structure, that the four uroplakins interact specifically forming two pairs, and that both uroplakin pairs are required for normal urothelial plaque formation.
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April 2001
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Research Article|
February 26 2001
Organization of uroplakin subunits: transmembrane topology, pair formation and plaque composition
Feng-Xia LIANG;
Feng-Xia LIANG
*Epithelial Biology Unit, The Ronald O. Perelmen Department of Dermatology, New York University Medical School, New York, NY 10016, U.S.A.
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Ina RIEDEL;
Ina RIEDEL
†Department of Pathology, Philipp University of Marburg, D-35033 Marburg, Germany
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Fang-Ming DENG;
Fang-Ming DENG
*Epithelial Biology Unit, The Ronald O. Perelmen Department of Dermatology, New York University Medical School, New York, NY 10016, U.S.A.
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Ge ZHOU;
Ge ZHOU
‡Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY 10016, U.S.A.
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Cong XU;
Cong XU
1
*Epithelial Biology Unit, The Ronald O. Perelmen Department of Dermatology, New York University Medical School, New York, NY 10016, U.S.A.
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Xue-Ru WU;
Xue-Ru WU
§Department of Urology, Kaplan Comprehensive Cancer Center, New York University Medical School, New York, NY 10016, U.S.A.
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Xiang-Peng KONG;
Xiang-Peng KONG
‡Skirball Institute of Biomolecular Medicine, New York University Medical School, New York, NY 10016, U.S.A.
ǁDepartment of Biochemistry, Kaplan Comprehensive Cancer Center, New York University Medical School, New York, NY 10016, U.S.A.
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Roland MOLL;
Roland MOLL
†Department of Pathology, Philipp University of Marburg, D-35033 Marburg, Germany
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Tung-Tien SUN
Tung-Tien SUN
2
*Epithelial Biology Unit, The Ronald O. Perelmen Department of Dermatology, New York University Medical School, New York, NY 10016, U.S.A.
§Department of Urology, Kaplan Comprehensive Cancer Center, New York University Medical School, New York, NY 10016, U.S.A.
¶Department of Pharmacology, Kaplan Comprehensive Cancer Center, New York University Medical School, New York, NY 10016, U.S.A.
2To whom correspondence should be addressed, at the Epithelial Biology Unit, The Ronald O. Perelmen Department of Dermatology (e-mail sunt01@med.nyu.edu).
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Publisher: Portland Press Ltd
Received:
October 02 2000
Revision Received:
January 03 2001
Accepted:
January 23 2001
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 2001
2001
Biochem J (2001) 355 (1): 13–18.
Article history
Received:
October 02 2000
Revision Received:
January 03 2001
Accepted:
January 23 2001
Citation
Feng-Xia LIANG, Ina RIEDEL, Fang-Ming DENG, Ge ZHOU, Cong XU, Xue-Ru WU, Xiang-Peng KONG, Roland MOLL, Tung-Tien SUN; Organization of uroplakin subunits: transmembrane topology, pair formation and plaque composition. Biochem J 1 April 2001; 355 (1): 13–18. doi: https://doi.org/10.1042/bj3550013
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