RNA chaperone that plays a key role in Cajal body formation (PubMed:24149844). Specifically recognizes and binds the Cajal body box (CAB box) present in both small Cajal body RNAs (scaRNAs) (PubMed:19285445). Probably acts by mediating localization of scaRNAs to Cajal bodies (PubMed:24149844). Belongs to the TCAB1 family.