The C-int::GAL4(21-881) hemidriver contains the gp41-1C split intein fragment fused to amino acids 21-881 of the Saccharomyces cerevisiae GAL4 gene ( SGDID:S000006169 ); the GAL4 fragment contains only part of the DNA-binding domain and is transcriptionally inactive. C-int::GAL4(21-881) forms one half of a 'split-intein GAL4' system: it is compatible with the GAL4(1-20)::N-int hemidriver that contains the N-terminal 20 amino acids of GAL4 fused to the gp41-1N split intein fragment (FBrf0256689). The gp41-1N and gp41-1C split intein fragments form a complementary pair which show efficient protein trans-splicing and a lack of cross-reactivity with other split intein fragments (PMID:22753413). In the 'split-intein GAL4' system, a functional transcriptional activator ('driver') is only reconstituted at the intersection of the expression patterns of the two hemidrivers; association between the gp41-1N and gp41-1C split intein fragments results in their self-excision and trans-splicing of the adjacent polypeptide sequence from each hemidriver, producing a complete GAL4 driver (FBrf0256689).