Cloning and sequence analysis of rainbow trout LMP 2 cDNA and differential expression of the mRNA

A Rainbow trout Oncorhynchus mykiss (L.) clone encoding the low molecular weight proteasome LMP 2 has been cloned and sequenced from rainbow trout leukocyte cells that had been stimulated with the mitogen phytohemagglutinin (PHA). The cDNA was 1254 bp and had an open reading frame of 648 bp encoding 217 amino acids. The sequence has a high degree of identity with other published LMP 2 sequences varying from 84·4% identity with medaka (Oryzias latipes) to 61·4% identity with Xenopus laevis. Northern blot analysis showed the LMP 2 mRNA to be expressed in a wide range of tissues, with two transcripts in gill, spleen and anterior kidney RNA. Up regulation of the LMP 2 mRNA transcript was shown in cells that were maintained in primary culture following stimulation with the PHA mitogen for 24 h. A 3·7-fold increase in mRNA was observed between control and stimulated cells.