Involved in the early to middle stages of 60S ribosomal subunit biogenesis. Core component of box C/D small nucleolar ribonucleoprotein (snoRNP) particles. Required for the biogenesis of box C/D snoRNAs such U3, U8 and U14 snoRNAs (By similarity). Part of a large pre-ribosomal ribonucleoprotein (RNP) complex, that consists of at least 62 ribosomal proteins, 45 nonribosomal proteins and both pre-rRNA and mature rRNA species. Within this complex directly interacts with TCOF1 in an RNA-independent manner. Core component of box C/D small nucleolar ribonucleoprotein (snoRNP) particles; the core proteins SNU13, NOP56, NOP58 and FBL assemble stepwise onto the snoRNA. Interacts NOP1 and NOP58. Interacts with NUFIP1, RUVBL1 and RUVBL2; RUVBL1:RUVBL2 seem to bridge the association of NOP56 with NUFIP1 (By similarity). Belongs to the NOP5/NOP56 family.