%A Carmel,Liran %A Chorev,Michal %D 2012 %J Frontiers in Genetics %C %F %G English %K exon junction complex,gene architecture,intron function,intron positional conservation,intron-exon structure,noncoding RNAs,regulation of expression,Splicing %Q %R 10.3389/fgene.2012.00055 %W %L %M %P %7 %8 2012-April-13 %9 Review %+ Dr Liran Carmel,The Hebrew University of Jerusalem,Genetics,Department of Genetics, The Alexander Silberman Institute of Life Sciences, Faculty of Science,,The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram,Jerusalem,91904,Israel,carmell@cc.huji.ac.il %# %! The function of introns %* %< %T The Function of Introns %U https://www.frontiersin.org/articles/10.3389/fgene.2012.00055 %V 3 %0 JOURNAL ARTICLE %@ 1664-8021 %X The intron–exon architecture of many eukaryotic genes raises the intriguing question of whether this unique organization serves any function, or is it simply a result of the spread of functionless introns in eukaryotic genomes. In this review, we show that introns in contemporary species fulfill a broad spectrum of functions, and are involved in virtually every step of mRNA processing. We propose that this great diversity of intronic functions supports the notion that introns were indeed selfish elements in early eukaryotes, but then independently gained numerous functions in different eukaryotic lineages. We suggest a novel criterion of evolutionary conservation, dubbed intron positional conservation, which can identify functional introns.