Human lactase-phlorizin hydrolase is not processed by furin, PC1/PC3, PC2, PACE4 and PC5/PC6A of the family of subtilisin-like proprotein processing proteases.
Human lactase-phlorizin hydrolase (LPH, EC 3.2.1.23/62) is synthesized as a single-chain precursor glycoprotein (pro-LPH) with a relative molecular mass of just over 200 kDa. Maturation to the mature enzyme (m-LPH, 160 kDa) occurs after passage of pro-LPH through the Golgi complex and involves the proteolytic removal of a 849 amino acid propeptide. The role of this propeptide as well as its removal is not fully understood and the proteolytic enzyme or enzymes involved are unknown. We studied the potential role of five different members of the family of subtilisin-like proprotein processing proteases in the maturation process of human LPH using a vaccinia virus based coexpression system in pig kidney PK(15) cells. Infected/transfected PK(15) cells expressed full-length pro-LPH but no maturation to m-LPH was observed. Coexpression of human pro-LPH with human furin, human PC1/PC3, human PC2, human PACE4 and mouse PC6A in PK(15) cells did not result in maturation of the enzyme. Cleavage and secretion of von Willebrand factor precursor (pro-vWF) was used as a positive control. None of the five proprotein processing proteases tested were capable of cleaving human pro-LPH, strongly suggesting that they are not involved in the maturation of this enzyme.
Wüthrich
M
M
Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Berne, Switzerland.
Creemers
J W
JW
van de Ven
W J
WJ
Sterchi
E E
EE
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D002460:Cell Line; D010450:Endopeptidases / Q000378:metabolism*; D004792:Enzyme Precursors / Q000378:metabolism*; D045683:Furin; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D007668:Kidney; D010694:Lactase-Phlorizin Hydrolase / Q000378:metabolism*; D051379:Mice; D045664:Proprotein Convertase 1; D045706:Proprotein Convertase 2; D045702:Proprotein Convertase 5; D043484:Proprotein Convertases; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012697:Serine Endopeptidases / Q000378:metabolism; D013381:Subtilisins / Q000378:metabolism*; D013552:Swine; D014162:Transfection / Q000235:genetics; D014841:von Willebrand Factor / Q000378:metabolism
D004792:Enzyme Precursors; D011498:Protein Precursors; C096385:pro-lactase-phlorizin hydrolase; D014841:von Willebrand Factor; C067003:von Willebrand factor propolypeptide; D010694:Lactase-Phlorizin Hydrolase; D010450:Endopeptidases; C080654:PCSK6 protein, human; C513086:Pcsk6 protein, mouse; D045702:Proprotein Convertase 5; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; D013381:Subtilisins; C473805:propeptide convertase 5, mouse; D045683:Furin; C473656:Pcsk1 protein, mouse; D045664:Proprotein Convertase 1; D045706:Proprotein Convertase 2; D016282:Aspartic Acid Endopeptidases