Figure 5. Filtering relation of MHC class I peptide optimization.
(A) Consider a population of 
MHC complexes containing peptides with off-rate 
. 
denotes the expected number of MHC complexes that will egress before the peptide can escape. 
denotes the expected proportion of egressed MHC complexes that will contain peptides with off-rate 
. This defines a measure of peptide optimization. We plot 
and 
as functions of 
for three peptides with different off-rates and the same initial populations. Maximal optimization is achieved when 
, with 
(dashed lines). (B) Consider a population of 
tapasin-MHC complexes containing peptides with off-rate 
. 
denotes the expected number of MHC complexes that will unbind from tapasin and egress before the peptide can escape, where 
. 
is defined as in A. We plot 
and 
as functions of 
with 
(black line in A). Maximal optimization is achieved when 
, with 
.