PSPA measures pT, so at flanking positions the pS row is a duplicate of the pT row. At position 0 the acceptor identity (pS, pT, pY) is genuine.

Signed attribution PSSM distilled from the CDDM discriminative MLP (in-silico saturation mutagenesis). Letters above 0 are enriched, below are depleted; this is not a probability distribution.