KZip+ consists of the DNA-binding domain of the Saccharomyces cerevisiae GAL4 gene ( SGDID:S000006169 ) fused to the Zip+ artificial leucine zipper domain (the EE[[12]]RR[[345]]L zipper from PMID:11344333). It is designed to act as a dominant-negative repressor of activity in the 'Split GAL4' system (FBrf0235757). The Zip+ leucine zipper heterodimerizes with the Zip- artificial leucine zipper domain (the RR[[12]]EE[[345]]L zipper from PMID:11344333) that is commonly fused to the Scer\GAL4 DNA-binding domain in the Split GAL4 system (FBrf0193617), for example in the GAL4(DBD)::Zip- hemidriver. The Zip+/Zip- interaction promotes the formation of a KZip+-GAL4(DBD)::Zip- dimer that contains two GAL4 DNA-binding domains, but no activation domain. Although this dimer can bind the UAS DNA sequence, it cannot promote transcription. KZip+ will thus compete with an activation domain-Zip+ ('AD-Zip+') hemidriver (such as VP16(AD)::Zip+ or p65(AD)::Zip+) and attenuate the formation of transcriptionally active GAL4(DBD)::Zip--AD-Zip+ dimers (FBrf0235757).