Sometimes genes are arranged nonrandomly on the chromosomes of eukaryo
tes. This review considers instances of gene clusters in which two gen
es or more are expressed from a single promoter. This includes cases i
n which a polycistronic pre-mRNA is processed to make monocistronic mR
NAs in nematodes, as well as isolated examples of polycistronic mRNAs
found in mammals, flies, and perhaps plants. (C) 1998 John Wiley & Son
s, Inc.