SMT3 gene from nematode, Caenorhabditis elegans, was identified and sequenced. The nematode SMT3 gene codes for a homolog to the yeast SMT3, suppressor of MIF2 mutation in a centromere protein gene. Further, nematode SMT3 cDNA was amplified by polymerase chain reaction from a cDNA library and its nucleotide sequence determined. A comparison of the SMT3 genomic and cDNA sequences established that the protein-encoding sequence is interrupted by two introns of 56 and 50 bp at codon Nos. 22-23 and 56, respectively. The sequence of 91 amino acids deduced from the nematode SMT3 nucleotide sequence exhibited 42 and 47% identity to the yeast and human SMT3 protein sequences, respectively. The evolutionary relationships of SMT3 proteins from human, nematode, Arabidopsis, rice, and yeast were analyzed.