Protein sequence alignment and AlphaFold analyses of the putative MBR on Pbp1. (A) AlphaFold 3 complex prediction of S. cerevisiae Mkt1 and Pbp1. pTM (0.61) and ipTM (0.81) did not reflect a highly confident interaction, but this was due to Pbp1 protein disordered regions driving down these scores. Highlighted in dark blue on the PAE plot is the predicted Pbp1 structure corresponding to approximately aa 491–549. Highlighted in red are the corresponding ordered parts of Mkt1. PAE plot regions between Pbp1 aa 491–549 and Mkt1 have low expected position error, suggesting a possible interaction (Abramson et al., 2024). (B) AlphaFold 3 predictions of S. cerevisiae full-length Mkt1 in complex with Pbp1 aa 491–549, aa 432–490, and aa 550–608. pTM and ipTM scores for the Mkt1/Pbp1-MBR (aa 491–549) complex indicated a high-quality prediction that might be similar to the true structure. In the cases of the other two predicted complexes, ipTM scores < 0.6 indicated likely failed predictions. (C) Alignment of Pbp1 protein sequences from yeast species generated using Clustal Omega. Two aa stretches in S. cerevisiae Pbp1, aa 500–503 and aa 536–538, are highly conserved across yeast species.