Algorithms|Amino Acid Sequence|Cluster Analysis|Databases, Protein|Evolution, Molecular|Genetic Variation|Glutamate-Ammonia Ligase|Glutamate-Cysteine Ligase|Models, Genetic|Models, Statistical|Molecular Sequence Data|Pattern Recognition, Automated|Proteins|Ribonucleoproteins, Small Nuclear|Sequence Alignment|Sequence Analysis, Protein|Sequence Homology, Amino Acid