Editorial: Characterizing the uncharacterized human proteins.

the number of non-canonical isoforms is almost equal to the number of canonical ones, suggesting that "non-canonical " isoforms may be equally important as their canonical counterparts. Despite the fact that scientists have studied canonical isoforms in greater detail over the years, there are still hundreds to thousands of uncharacterized canonical and non-canonical isoforms as their biological functions are yet to be revealed. Besides, the discovery of protein encoding ncRNAs (Jackson et al., 2018) has added another layer of complexity to the situation, and as such, the current reported total number of human proteoforms (Smith and Kelleher, 2018) is likely to be underestimated.The Research Topic titled "Characterizing the uncharacterized human proteins" showcases the latest discoveries in the field of unstudied or under-studied proteins/isoforms. It consists of 9 published manuscripts, including 6 research articles and 3 reviews, with 66 different contributors.This Research Topic covers a wide range of topics, from individual uncharacterized proteins to highthroughput analyses of novel peptides/protein variants in both normal physiological and pathological conditions.