This family includes the N terminal region of TORC proteins. TORC (Transducer of regulated CREB activity) is a protein family of coactivators that enhances the activity of CRE-depended transcription via a phosphorylation-independent interaction with the bZIP DNA binding/dimerisation domain of CREB (cAMP Response Element-Binding) [2]. The proteins display a highly conserved predicted N-terminal coiled-coil domain and an invariant sequence matching a protein kinase A (PKA) phosphorylation consensus sequence (RKXS) [1]. The coiled-coil structure interacts with the bZIP domain of CREB [2]. This interaction may occur via ionic bonds because it is disrupted under high-salt conditions [3]. In addition to CREB-binding, the N-terminal region plays a role in the tetramer formation of TORCs [2], but the physiological function of the multimeric complex has not been clarified yet.

1: Identification of a family of cAMP response element-binding protein coactivators by genome-scale functional analysis in mammalian cells. Iourgenko V, Zhang W, Mickanin C, Daly I, Jiang C, Hexham JM, Orth AP, Miraglia L, Meltzer J, Garza D, Chirn GW, McWhinnie E, Cohen D, Skelton J, Terry R, Yu Y, Bodian D, Buxton FP, Zhu J, Song C, Labow MA; Proc Natl Acad Sci U S A. 2003;100:12147-12152. PMID:14506290

2: TORCs: transducers of regulated CREB activity. Conkright MD, Canettieri G, Screaton R, Guzman E, Miraglia L, Hogenesch JB, Montminy M; Mol Cell. 2003;12:413-423. PMID:14536081

3: TORC-SIK cascade regulates CREB activity through the basic leucine zipper domain. Takemori H, Kajimura J, Okamoto M; FEBS J. 2007;274:3202-3209. PMID:17565599