  Protein folding and evolution are intimately linked phenomena. Here, we
revisit the concept of exons as potential protein folding modules across 38
abundant and conserved protein families. Taking advantage of genomic
exon-intron organization and extensive protein sequence data, we explore exon
boundary conservation and assess their foldon-like behavior using energy
landscape theoretic measurements. We found deviations in exon size distribution
from exponential decay indicating selection in evolution. We describe that
there is a pronounced independent foldability of segments corresponding to
conserved exons, supporting the exon-foldon correspondence. We further develop
a systematic partitioning of protein domains using exon boundary hot spots,
unveiling minimal common exons consisting of uninterrupted alpha and/or beta
elements for the majority but not all of the studied families.
