Cellular prion protein (PrPC ) misfolds to infectivity-associated PrPS c and generates carboxyl-terminal fragments C1 and C2 in healthy and prion-infected animals. C1 cleavage occurs amino-terminal of PrPC 's hydrophobic domain, while the larger C2 fragment is generated by cleavage at the end of the octarepeat region. Since the PrP-like proteins Dpl and Sho are reported to inhabit similar membrane environments to PrPC , we investigated endoproteolysis using a panel of mutant alleles. Dpl undergoes efficient in vivo cleavage at a C1 site mapped to the start of the globular domain, which is a structurally similar cleavage site to PrPC . Sho is processed to C1 and C2 fragments and proved refractory to mutagen... More
Cellular prion protein (PrPC ) misfolds to infectivity-associated PrPS c and generates carboxyl-terminal fragments C1 and C2 in healthy and prion-infected animals. C1 cleavage occurs amino-terminal of PrPC 's hydrophobic domain, while the larger C2 fragment is generated by cleavage at the end of the octarepeat region. Since the PrP-like proteins Dpl and Sho are reported to inhabit similar membrane environments to PrPC , we investigated endoproteolysis using a panel of mutant alleles. Dpl undergoes efficient in vivo cleavage at a C1 site mapped to the start of the globular domain, which is a structurally similar cleavage site to PrPC . Sho is processed to C1 and C2 fragments and proved refractory to mutagenesis to inactivate C1 cleavage. As a reciprocal product of C1 cleavage, Sho also engenders a metabolically stable N1 fragment with a carboxyl-terminus after its hydrophobic domain, an observation that may account for N1's association with membrane and/or cellular fractions in vitro and in vivo. Our data indicate that glycosylation status and yet-to-be-identified proteases modulate internal C1 and C2 proteolysis events within the mammalian prion protein family.
