Fin (formerly known as YabK) is a small protein required for efficient switching from sigma(F)- to sigma(G)-directed gene expression during sporulation in Bacillus subtilis. Fin has been proposed to be an anti-sigma(F) factor which, by disabling sigma(F), promotes the switch to late developmental gene expression in the forespore [1].

1: A small protein required for the switch from {sigma}F to {sigma}G during sporulation in Bacillus subtilis. Camp AH, Wang AF, Losick R; J Bacteriol. 2011;193:116-124. PMID:21037003