The UniProtKB database (www.uniprot.org) is the world's leading high-quality, comprehensive and freely accessible resource of protein sequence and functional information. A proteome comprises of all the proteins produced by the transcripts translated from a genome, including isoforms and proteins/peptides produced by cleavage of the initial transcript into smaller peptides and polypeptides. For each experimentally-studied protein in a proteome UniProtKB presents the user with a summary of experimentally verified, or computationally predicted, functional information added by our expert biocuration team. This includes additional modifications in both sequence and function caused by nonsynonymous variants and posttranslational modifications. Computationally transferred or predicted annotations are added to those proteins which have not been functionally studied (unreviewed entries). We present here revisions to our proteomics peptide mapping pipeline, in line with HPP3.0 guidelines, a summary of recent updates to the UniProt resource, including visualization of proteins in the context of protein complexes in collaboration with the Complex Portal, and an overview of the current state of the human proteome.