Ubiquitins (polyubiquitin and ubiquitin extension protein) in marine sponges: cDNA sequence and phylogenetic analysis

The complete nucleotide sequences of twoSuberites domunculacDNAs and oneSycon raphanuscDNA, all encoding ubiquitin, have been determined. One cDNA fromS. domunculacodes for polyubiquitin with four tandemly repeated monomeric units and the second cDNA encodes ubiquitin fused to a ribosomal protein of 78 amino acids (aa).S. domunculapossesses at least one additional polyubiquitin gene, from which the last two monomers were also sequenced. All analysed genes fromS. domunculaencode identical ubiquitin proteins, with only one aa difference (Ala19) to the human/higher animals ubiquitin (Pro19). Ubiquitin inS. domunculais identical with the ubiquitin found in another Demospongia,Geodia cydonium. T…