Introduction of LAPTM4B
LAPTM4B, Lysosomal-associated transmembrane protein 4B, is a protein that in humans is encoded by the LAPTM4B gene. LAPTM4B protein contains a lysosome localization motif and localizes on late endosomes and lysosomes. The expression level of LAPTM4B is relatively high in breast, liver, lung, ovarian, uterine, gastric cancers. It can be utilized to be a therapeutic target to prevent chemotherapy resistance or a marker to identify the patients who will not benefit from anthracyclines.
|Basic Information of LAPTM4B|
|Protein Name||Lysosomal-associated transmembrane protein 4B|
|Aliases||Lysosome-associated transmembrane protein 4-beta, PSEC0001|
|Organism||Homo sapiens (Human)|
Function of LAPTM4B Membrane Protein
LAPTM4B contains a lysosome localization motif and localizes on late endosomes and lysosomes. It is required for optimal lysosomal functions. It can block EGF-stimulated EGFR intraluminal sorting and degradation, while the inhibition function can be reversed by binding with the phosphatidylinositol 4,5-bisphosphate. Also, it can recruit SLC3A2 and SLC7A5 (the Leu transporter) to the lysosome, then result in promoting entry of leucine and other essential amino acids (EAAs) into the lysosome which can stimulate activation of proton-transporting vacuolar (V)-ATPase protein pump (V-ATPase) and hence mTORC1 activation. In addition, it plays a role as a negative regulator of TGFB1 production in regulatory T cells, and can bind ceramide and facilitates its exit from late endosome in order to control cell death pathways. Some clinical reports have shown that LAPTM4B can be utilized as a therapeutic target to prevent chemotherapy resistance or a marker to identify the patients who will not benefit from anthracyclines.
Fig.1 mechanisms for LAPTM4B promoting cancer development (Meng, 2016)
Application of LAPTM4B Membrane Protein in Literature
This article demonstrates the mechanistic insights into how transmembrane proteins sense and respond to ceramide, and indicates that LAPTM4B controls amino acid transporter interaction.
This article shows the possible role of the LAPTM4B gene in anthracycline resistance in HR- breast cancer and analyzing LAPTM4B copy number pattern may support future treatment decision.
This study suggests that genetic polymorphisms of LAPTM4B are not a risk factor for the development of DLBCL, but the LAPTM4B*2 allele may a better prognostic indicator in patients with IPI score 3-5 in DLBCL.
This article demonstrates that AP4 promotes cell growth, migration, invasion, and cisplatin resistance through upregulation of LAPTM4B expression, thus representing an attractive therapeutic target for breast cancer.
This article provides evidence of the expression and functional coupling between AP4 and LAPTM4B and sheds light on the regulation of LAPTM4B and its function in liver cancer.
LAPTM4B Preparation Options
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