Target of rapamycin complex 2 subunit MAPKAP1 is a protein similar to the yeast SIN1 protein, a stress-activated protein kinase. Alternatively spliced transcript variants encoding distinct isoforms have been described. Alternate polyadenylation sites as well as alternate 3' UTRs have been identified for transcripts of this gene.
The deduced 522-amino acid protein has a nuclear localization signal, 2 bipartite nuclear localization signals, a peroxisomal targeting signal, and a PEST motif for rapid protein degradation. Comparison of SIN1 with homologs from various species revealed a short, highly conserved region, designated Box1, located within a larger conserved domain, designated CRIM (conserved region in middle).