The GAL4(1-20)::N-int hemidriver contains the N-terminal 20 amino acids of the Saccharomyces cerevisiae GAL4 gene ( SGDID:S000006169 ) fused to the gp41-1N split intein fragment; the GAL4 fragment contains only part of the DNA-binding domain and is transcriptionally inactive. GAL4(1-20)::N-int forms one half of a 'split-intein GAL4' system: it is compatible with a hemidriver that contains the gp41-1C split intein fragment fused to sequence encoding the remainder of the GAL4 DNA-binding domain (residues 21-93) plus transcriptional activation domain sequence (this may simply be the remainder of the GAL4 coding sequence, as in C-int::GAL4(21-881), or may be a fusion of GAL4 residues 21-93 with transcriptional activation domain(s) from a different gene, as in C-int::GAL4(21-93)::GS) (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 single functional driver protein composed of a reconstituted complete GAL4 DNA-binding domain plus transcriptional activation domain(s) derived from the gp41-1C-containing hemidriver (FBrf0256689).