What are "+" and "Ar" in consensus binding sequence of amino acids?
Ar means aromatic and + means positively charged residues. However, this is not a standard code (as of now).

From the same paper:


  Sequences closely matching these optimal binding motifs, R-X-[Ar/S]-[+]-pS-[LEAM]-P and R-[S/Ar]-[+]-pS-[LEAM]-P, denoted as mode 1 and mode 2 consensus sequences, were found to be present in many known 14-3-3 ligands ( Yaffe et al. 1997), where Ar denotes aromatic residues and + denotes basic residues.