title: Measurement of the Activity of the Atg4 Cysteine Proteases.
abstract: While only one Atg4 is present in yeast, there are four Atg4 homologues in human and in mouse with different substrate specificities and catalytic efficiencies. The molecule Atg4 is a type of cysteine protease, and is known for its crucial roles in cleavage of the Atg8 family proteins before they can be conjugated to phospholipids, and also in cleavage of the conjugated Atg8 molecules from the membrane, a process known as deconjugation. Both processes are required for the maximal efficiency in autophagosome biogenesis. Atg4 could thus be a target for intervention of the autophagy process. It is thus important to measure Atg4 activity to determine and to modulate the autophagy function. Here, we review the catalytic functions and regulatory mechanisms of human Atg4 proteases and discuss the methodology for analyzing Atg4 activity in details.
authors.affiliation: School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, China. Electronic address: limin65@mail.sysu.edu.cn.
authors.forename: M
authors.initials: M
authors.lastname: Li
authors.affiliation: School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Fu
authors.affiliation: School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Indiana University School of Medicine, Indianapolis, IN, United States. Electronic address: xmyin@iupui.edu.
authors.forename: X-M
authors.initials: XM
authors.lastname: Yin
mesh_terms: D000071190:Autophagy-Related Protein 8 Family / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D000071183:Autophagy-Related Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D057166:High-Throughput Screening Assays; D006801:Humans; D007700:Kinetics; D008967:Molecular Biology / Q000379:methods*; D011487:Protein Conformation; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics
chemical_list: D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D011994:Recombinant Proteins; C474025:ATG4A protein, human; D003546:Cysteine Endopeptidases
keywords: Atg4; Atg8; Enzymatic kinetics; FRET; GABARAP; GATE-16; High-throughput screening; LC3