Liver Cancer
Copyright ©The Author(s) 2004. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 1, 2004; 10(11): 1555-1559
Published online Jun 1, 2004. doi: 10.3748/wjg.v10.i11.1555
Structure analysis and expressions of a novel tetratransmembrane protein, lysosoma-associated protein transmembrane 4 β associated with hepatocellular carcinoma
Xin-Rong Liu, Rou-Li Zhou, Qing-Yun Zhang, Ye Zhang, Yue-Ying Jin, Ming Lin, Jing-An Rui, Da-Xiong Ye
Xin-Rong Liu, Rou-Li Zhou, Ye Zhang, Yue-Ying Jin, Ming Lin, Department of Cell Biology and Genetics, School of Basic Medical Sciences, Peking University, Beijing 100083, China
Qing-Yun Zhang, Department of Clinical Laboratory, School of Oncology, Peking University, Beijing 100037, China
Jing-An Rui, Da-Xiong Ye, Department of General Surgery/Pathology, Peking Union Medical College Hospital, Beijing 100032, China
Author contributions: All authors contributed equally to the work.
Supported by the 248 Major R&D Program of Beijing, No. H020220020310 and Special Fund for Promotion of Education, Ministry of Education, China
Correspondence to: Dr. Rou-Li Zhou, Department of Cell Biology and Genetics, School of Basic Medical Sciences, Peking University, Beijing 100083, China.
Telephone: +86-10-82801034 Fax: +86-10-62358270
Received: July 12, 2003
Revised: July 18, 2003
Accepted: July 30, 2003
Published online: June 1, 2004

AIM: To analyze the structure and expressions of the protein encoded by an HCC-associated novel gene, lysosome-associated protein transmembrane 4 β (LAPTM4B).

METHODS: Primary structure and fundamental characteristics of LAPTM4B protein were analysed with bioinformatics. Expressions of LAPTM4B in HCC tissues and various cell lines were detected using polyclonal antibodies and Western blot.

RESULTS: LAPTM4B encoded two isoforms of proteins with molecular masses 35-ku and 24-ku, respectively. The expression level of LAPTM4B-35 protein in HCC tissues was dramatically upregulated and related to the differentiation status of HCC tissues, and it was also high in some cancer cell lines. Computer analysis showed LAPTM4B was an integral membrane protein with four transmembrane domains. LAPTM4B showed relatively high homology to LAPTM4A and LAPTM5 in various species.

CONCLUSION: LAPTM4B gene encoded two isoforms of tetratransmembrane proteins, LAPTM4B-35 and LAPTM4B-24. The expression of LAPTM4B-35 protein is upregulated and associated with poor differentiation in human HCC tissues, and also at high levels in some cancer cell lines. LAPTM4B is an original and conserved protein.

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