The C-termini are often very important for protein function, often containing short contiguous peptide sequences (minimotifs) that encode post-translational modification, zipcode motifs for trafficking to specific cell compartments, and minimotifs for binding to other proteins and molecules. Through our annotation of 100,000s of minimotifs in the Minimotif Miner database our lab has catalogued >1000 known functional minimotifs specific to the carboxy (C)-termini of proteins. These C-terminal minimotifs are critica for a wide array of biological functions. Mutations can disable minimotifs by a single point mutation producing disease states and some minimotif mimetics are FDA-approved drugs used to treat patients. In this proposal we seek to identify new minimotifs and consolidate existing information into what we coin the "functional C-terminome", the general role of the C-terminus in all human proteins. We first ask the question: Are there important C-terminal minimotifs that remain to be discovered? In our preliminary studies two graduate students performed a bioinformatic analysis to identify many possible minimotif patterns that overrepresented on the C- termini of different human proteins when compared to a scrambled human proteome. We next selected four of these minimotifs and in a pilot screen an undergraduate used affinity chromatography followed by mass spectrometry to identify potential binding partners for these minimotifs. We propose to expand upon these findings by (1) determining the relevance of the PxP-carboxy terminal minimotif in stimulate exocytosis as a case study, (2) identify interactors of novel C-terminal motifs by affinity capture and mass spectrometry (LC MS/MS), and (3) to consolidate all known information about the functional C-terminome and generate a searchable webpage for exploring all C-terminal minimotifs in the human proteome.
C-terminal minimotifs are critical for a wide array of protein functions and some minimotif mimetics are used as drugs to treat patients. Here, we propose to use and affinity/mass spectrometry screen to identify and validate new C-terminal minimotifs, consolidate existing information and disseminate information about C- terminal minimotifs on a new functional C-terminome website.