Structure analysis and expressions of a novel tetratransmembrane protein, lysosoma-associated protein transmembrane 4 beta associated with hepatocellular carcinoma.
OBJECTIVE
To analyze the structure and expressions of the protein encoded by an HCC-associated novel gene, lysosome-associated protein transmembrane 4 beta (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.


CONCLUSIONS
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.
Liu
Xin-Rong
XR
Department of Cell Biology and Genetics, School of Basic Medical Sciences, Peking University, Beijing 100083, China. rlzhou@bjmu.edu.cn
Zhou
Rou-Li
RL
Zhang
Qing-Yun
QY
Zhang
Ye
Y
Jin
Yue-Ying
YY
Lin
Ming
M
Rui
Jing-An
JA
Ye
Da-Xiong
DX
D000595:Amino Acid Sequence; D018286:Carcinoma, Giant Cell; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D045744:Cell Line, Tumor; D019295:Computational Biology; D006367:HeLa Cells; D006801:Humans; D007536:Isomerism; D008113:Liver Neoplasms / Q000378:metabolism*; D008175:Lung Neoplasms; D008247:Lysosomes / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008545:Melanoma; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011471:Prostatic Neoplasms; D017434:Protein Structure, Tertiary
C477083:LAPTM4B protein, human; D008565:Membrane Proteins; D015513:Oncogene Proteins