In decipher package, how can I write a pattern for a sequence

I am trying to match a pattern of sequence using decipher package.

How to write the following as a pattern? So I can match letters (based on positions)

seq: ··········QM·N···············AP······DF·I··L·············Q····M··QT·R··T·RN·············G······RS·T·····I···TT···········Y·····H······L····

library(DECIPHER)
BrowseSeqs(AA, highlight =2, pattern= ??????, colorPatterns = TRUE)

For Example:

I have a file like this, It should match the pattern for above sequence

seq: ..........QM.N.
seq1:..........MM...
seq2:..........Q..N.

the pattern should match Q in position 11(seq,seq2), M in position 12 (seq,seq1) and N in position 14(seq, seq3)