[Identification and characterization of LAPTM4B encoded by a human hepatocellular carcinoma-associated novel gene].
OBJECTIVE
To identify and characterize the novel proteins encoded by a HCC-associated novel gene, LAPTM4B (lysosomeassociated protein transmembrane 4 beta).


METHODS
The novel proteins was identified by Western blot, immunohistochemistry and 2D electrophoresis; the molecular interactions were studied by co-immunoprecipitation.


RESULTS
LAPTM4B encoded two isoforms of proteins with molecular weight 35 x 10(3) and 24 x 10(3) and pI 9.07 and 4.65, respectively. The expression levels of LAPTM4B proteins in HCC tissues and cell lines were upregulated and related to differentiation, and most dramatically raised for 35 x 10(3) one. It was demonstrated that LAPTM4B--integrin alpha 6 and LAPTM4B--EGFR signaling complexes were formed when BEL-7402 cells were seeded on laminin substrate.


CONCLUSIONS
The LAPTM4B-35 protein is overexpressed in human HCC tissues and cell lines and may involve in signal transduction triggered by extracellular matrix via interaction with integrin alpha 6 and EGFR on cell surface.
Liu
Xinrong
X
Department of Cell Biology and Genetics, Peking University School of Basic Medical Sciences, Beijing 100083, China.
Zhou
Rouli
R
Zhang
Qingyun
Q
Zhang
Ye
Y
Shao
Genze
G
Jin
Yueying
Y
Zhang
Sha
S
Lin
Ming
M
Rui
Jing'an
J
Ye
Daxiong
D
D006528:Carcinoma, Hepatocellular / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D015513:Oncogene Proteins / Q000235:genetics*; D015398:Signal Transduction; D015854:Up-Regulation
C477083:LAPTM4B protein, human; D008565:Membrane Proteins; D015513:Oncogene Proteins