4 | Conclusion
As microproteins are increasingly linked with roles in human health and
disease, elucidating their numbers and biological roles will be ever
more essential. Regarding the complete annotation of microproteins,
while there are still inconsistencies in the specific sORF loci
identified across ribosome profiling studies, most recent studies detect
comparable numbers of translated sORFs in a given organism. This
developing consensus suggests that meta-analysis of ribosome profiling
data has the potential to resolve complete sORF translatomes in the near
future. As this effort advances, large-scale CRISPR screens and other
methods can be (re-)employed to identify functional sORFs on scale.
However, it is important to note that most sORF functional screens to
date have focused on cell proliferation/survival, protein-protein
interactions, and/or conservation, thus potentially screening out sORFs
with roles beyond these readouts. For example, microproteins with clear
involvement in yeast mating and cellular responses to stress have been
reported, but can be species-specific, nonessential and may not undergo
long-lived interactions with other proteins, and thus would not appear
as hits in most functional screens to date. Thus, alternative avenues to
identify microproteins with potential functions are needed. Given the
exquisite link between protein three-dimensional structure and function,
investigation of microprotein structure holds tremendous promise to
address this need. The advent of AlphaFold, combined with the rapidly
increasing number of solved microprotein structures and experimentally
characterized intrinsically disordered microproteins, including those
described above, are already contributing to the improved power of
structural prediction to generate functional hypotheses about
uncharacterized microproteins. Experimental structural investigations
are also providing critical mechanistic insights into how microproteins
exert their functions, for example in allosteric regulation of target
proteins. Combined with insights into disease-associated microprotein
mutations and dysregulation, structural and mechanistic information may
also pave the way to determining whether microproteins and/or their
binding partners are druggable in the future.