TECHNICAL INNOVATION: We also demonstrated that I2MS for fragment ion analysis (I2MS2) increases catenin top-down sequence coverages from <1% to ~30%. We expect future instrumentation advances will improve proteoform-level analysis of these LARGE structural proteins/complexes. (7/7)

BIOLOGY TAKEAWAY: We proposed a catenin phospho-code—where combinatorial phosphorylation of these large proteoforms works with mechanical signals to drive cadherin–catenin organization and #adherensjunction function. (6/7)

Using bottom-up proteomics/antibodies, we confirmed that some phosphorylations appear constitutive, while others are more sensitive to myosin inhibition, raising the possibility of a mechano-sensitive “phospho-code” for cell-cell adhesion. (5/7)

Remarkably, catenin phosphorylation is sensitive to drugs that modulate #actomyosin contractility. We observed HYPER-phosphorylation on catenins under conditions that promote cell rounding and HYPO-phosphorylation when myosin activity was reduced. (4/7)

With Team @carajgottardi.bsky.social ‘s expertise in cell-cell adhesion, we purified cadherin-associated catenins and profiled their proteoforms using I2MS and found #phosphorylation to be the MAJOR modification. (3/7)

Team @nlkproteomics.bsky.social has developed individual ion mass spectrometry (I2MS) for proteoform analysis. We extend the current ~70 kDa mass limit beyond 100 kDa in this work. (2/7)