This leucine-zipper is towards the N-terminus of MIP1 proteins. These proteins, here largely from plants, are subunits of the TORC2 (rictor-mTOR) protein complex controlling cell growth and proliferation [2]. The leucine-zipper is likely to be the region that interacts with plant MADS-box factors [1],

1: An antirrhinum ternary complex factor specifically interacts with C-function and SEPALLATA-like MADS-box factors. Causier B, Cook H, Davies B; Plant Mol Biol. 2003;52:1051-1062. PMID:14558664

2: SIN1/MIP1 maintains rictor-mTOR complex integrity and regulates Akt phosphorylation and substrate specificity. Jacinto E, Facchinetti V, Liu D, Soto N, Wei S, Jung SY, Huang Q, Qin J, Su B; Cell. 2006;127:125-137. PMID:16962653