The full length human protein has 270 amino acids (31 kDa) with a centrally located RNA binding domain (RBD).

The 75 amino acid RBD is well conserved across species, however the remainder of SLBP is highly divergent in most organisms and not homologous to any other protein in the eukaryotic genomes.

Histone mRNAs do not contain introns or polyadenylation signals, and are processed by a single endonucleolytic cleavage event downstream of the stem-loop.

All SLBP proteins are capable of forming a highly stable complex with histone stem-loop RNA.

SLBP proteins also recognize the tetraloop structure of the histone hairpin, the base of the stem, and the 5' flanking region.