Homo sapiens C/D box snoRNA U24. This snoRNA was initially characterized by a bioinformatics search for C/D motives in a vertebrate intron database (Qu et al., 1995). It is predicted to guide the 2'O-ribose methylation of both 28S rRNA C2338 and C2352. It is however possible that, as in yeast, U24 might guide the methylation of adjacent bases G2351 and A2350 (Kiss-Laszlo et al., 1996), although the methylation of A2350 is predicted to be guided by U76. U24 shares the same host gene with the C/D box snoRNA U36A, U36B and U36C (RPL7A). A second copy of U24, U24A, is present in cow, opossum, zebrafish and xenopus RPL7A gene.