Abstract: RNase Y is an endoribonuclease that governs global mRNA turnover/processing in Ba-cillus subtilis and likely many other bacteria. The enzyme is anchored at the cell membrane, a pseudo-compartmentalization that appears coherent with its task to initiate decay of mRNAs translated predominantly at the cell periphery. However, the reason and consequence for RNase Y attachment to the membrane are largely unknown. We have studied a strain expressing wild-type levels of a cytoplasmic form of RNase Y from the chromosomal locus. This strain exhibits a slow growth phenotype similar to an RNase Y null mutant. Genome-wide data show a significant effect on the expression of hundreds of genes. Certain RNA substrates clearly require RNase Y membrane attachment but others do not. We found no correlation between mRNA stabilization and the cellular location or function of encoded proteins. The Y-complex, an RNase Y specificity factor, appears to also recognize the cytoplasmic form of the enzyme which is able to restore wild-type levels of the corresponding transcripts. We propose that membrane attachment of RNase Y is required for the functional interaction with many coding and non-coding RNAs, for limiting the cleavage of certain substrates and potentially to avoid unfavorable competition between RNase Y and other ribonucleases like RNase J that have a similar evolutionarily conserved cleavage speci-ficity.