Substrate Specificities of the Granzyme Tryptases A and K

The
physiological roles of the granzymes A and K have been debated,
especially concerning their involvement in cytotoxic and inflammatory
processes. By performing N-terminal COFRADIC assisted N-terminomics
on the homologous human granzymes A and K, we here provide detailed
data on their substrate repertoires, their specificities, and differences
in efficiency by which they cleave their substrates, all of which
may aid in elucidating their key substrates. In addition, the so far
uncharacterized mouse granzyme K was profiled alongside its human
orthologue. While the global primary specificity profiles of these
granzymes appear quite similar as they revealed only subtle differences
and pointed to substrate occupancies in the P1, P1′, and P2′
position as the main determinants for substrate recognition, differential
analyses unveiled distinguishing substrate subsite features, some
of which were confirmed by the more selective cleavage of specifically
designed probes.