caa a22 4500 397574428 CHVBK 20180308164851.0 cr unu---uuuuu 161202e199606 xx s 000 0 eng 10.1093/hmg/5.6.737 doi (NATIONALLICENCE)oxford-10.1093/hmg/5.6.737 Ser72Pro Active-Site Disease Mutation in Human Lysosomal Aspartylglucosaminidase: Abnormal Intracellular Processing and Evidence for Extracellular Activation [Elektronische Daten] [Minna Peltola, Ritva Tikkanen, Leena Peltonen, Anu Jalanko] Aspartylglucosaminuria (AGU) is a lysosomal storage disease caused by deficient activity of aspartylglucosaminidase (AGA). We report here a T214C mutation leading to a Ser72Pro substitution in four Arab families. This is the first naturally occurring AGU mutation involving an active-site amino acid of this recently crystallized hydrolase and it seems to represent the second most common AGU mutation worldwide. The intracellular consequences of the Ser72Pro mutation were analyzed by transient expression in COS-1 cells and we were able to demonstrate that this active-site mutation most probably does not destroy the enzyme activity per se, but specifically prevents the proteolytic activation cleavage of AGA in the endoplasmic reticulum (ER). The mutant enzyme is, however, folded correctly enough to allow mannose-6-phosphorylation and targeting to lysosomes. The overexpressed mutant enzyme remained inactive intracellularly, but the secreted mutant precursor was proteolytically activated extracellularly, resulting in a similar subunit composition to that in the wild-type AGA in the ER. The partially activated mutant enzyme was endocytosed further by the recipient cells. These data demonstrate that the proteolytic activation of AGA can also occur extracellularly and suggest that the driving mechanism of AGA precursor cleavage is autocatalytic. © 1996 Oxford University Press Peltola Minna Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland aut Tikkanen Ritva Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland aut Peltonen Leena Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland aut Jalanko Anu Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland aut Human Molecular Genetics Oxford University Press 5/6(1996-06), 737-743 0964-6906 5:6<737 1996 5 hmg https://doi.org/10.1093/hmg/5.6.737 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/hmg/5.6.737 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Peltola Minna Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland aut NATIONALLICENCE 700 1- Tikkanen Ritva Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland aut NATIONALLICENCE 700 1- Peltonen Leena Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland aut NATIONALLICENCE 700 1- Jalanko Anu Department of Human Molecular Genetics, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland aut NATIONALLICENCE 773 0- Human Molecular Genetics Oxford University Press 5/6(1996-06), 737-743 0964-6906 5:6<737 1996 5 hmg Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford