Table 1. The characteristics of different types of CircRNA.

Name	Type	Location	Joint site	Sequence feature	Function
ecRNA (Zhang et al., 2014)	exon	cytoplasms	3′–5′ phosphodiester bond	Formed by cyclization of exons containing the reverse complementary sequence of introns and selective cyclization.	Functioning as miRNA sponges; Interact with RNA-binding proteins (RBPs); Participates in translation.
CiRNA (Zhang et al., 2013)	intron	nucleus	2′-5′ phosphodiester bond	5′ splice site enriched with 7 GU motifs and 3′ branch site contains 11 C motifs.	Regulation of gene transcription.
ElciRNA (Li et al., 2017b)	exon–intron	nucleus	3′-5′ phosphodiester bond	Formed by cyclization of exons containing the reverse complementary sequence of introns and selective cyclization.	Regulation of gene transcription.

Notes:

ecRNA, exon circRNA; ciRNA, intron circRNA; ElciRNA, exon-intron circRNA.