Murine Apg12p has a substrate preference for murine Apg7p over three Apg8p homologs.
Apg7p is a unique E1 enzyme which is essential for both the Apg12p- and Apg8p-modification systems, and plays indispensable roles in yeast autophagy. A cDNA encoding murine Apg7p homolog (mApg7p) was isolated from a mouse brain cDNA library. The predicted amino acid sequence of the clone shows a significant homology to human Apg7p and yeast Apg7p. Murine Apg12p as well as the three mammalian Apg8p homologs co-immunoprecipitate with mApg7p. Site-directed mutagenesis revealed that an active-site cysteine within mApg7p is Cys(567), indicating that mApg7p is an authentic E1 enzyme for murine Apg12p and mammalian Apg8p homologs. The mutagenesis study also revealed that Apg12p has a substrate preference for mApg7p over the three Apg8p homologs, suggesting that the Apg12p conjugation by Apg7p occurs preferentially in mammalian cells compared with the modification of the three Apg8p homologs. We also report here on the ubiquitous expression of human APG7 mRNA in human adult and fetal tissues and of rat Apg7p in adult tissues.
Tanida
Isei
I
Department of Biochemistry, Juntendo University School of Medicine, Tokyo 113-8421, Japan.
Tanida-Miyake
Emiko
E
Nishitani
Tomohito
T
Komatsu
Masaaki
M
Yamazaki
Harumi
H
Ueno
Takashi
T
Kominami
Eiki
E
D000595:Amino Acid Sequence; D000818:Animals; D000071192:Autophagy-Related Protein 12; D000071193:Autophagy-Related Protein 7; D000071190:Autophagy-Related Protein 8 Family; D002460:Cell Line; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008025:Ligases / Q000235:genetics; D008297:Male; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014018:Tissue Distribution; D044767:Ubiquitin-Protein Ligases
C114830:ATG7 protein, S cerevisiae; C113757:ATG8 protein, S cerevisiae; C491971:Atg12 protein, mouse; D000071192:Autophagy-Related Protein 12; D000071190:Autophagy-Related Protein 8 Family; D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; D011506:Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D010088:Oxidoreductases; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D000071193:Autophagy-Related Protein 7