NPAS4 binds ARNT

NPAS4 is a basic-helix-loop-helix (bHLH) transcription factor that needs to dimerize with another bHLH protein in order to be able to bind to target DNA. ARNT (ARNT1) is a bHLH transcription factor that can form a transcriptionally active heterodimer with NPAS4 (Ooe et al. 2004). In vivo, endogenous Arnt and Npas4 can be co-immunoprecipitated from the mouse brain (Ooe et al. 2009) and from primary cultures of mouse brain slices (Brigidi et al. 2019). Based on a study using primary cultures of mouse brain slices, Npas4 induced by excitatory post-synaptic potentials (EPSPs) exclusively associates with Arnt both at 5 min, when Npas4 is in the dendrites and 60 min post-stimulation, after Npas4 has translocated to the nucleus. Npas4 and Arnt mRNAs co-localize in the dendrites and may be translated concurrently (Brigidi et al. 2019).

NPAS4作为一种基本的螺旋-环-螺旋（bHLH）转录因子，需与另一种bHLH蛋白形成二聚体，方能具备与靶DNA结合的能力。ARNT（ARNT1）是一种能够与NPAS4（Ooe等，2004年）形成转录活性异源二聚体的bHLH转录因子。在体内，内源性的Arnt与Npas4可从小鼠脑部（Ooe等，2009年）以及小鼠脑切片原代培养中共同免疫沉淀（Brigidi等，2019年）。基于对小鼠脑切片原代培养的研究，兴奋性突触后电位（EPSPs）诱导的Npas4在5分钟时，即Npas4位于树突时，以及刺激后60分钟，即Npas4已转移至细胞核后，均专一性地与Arnt结合。Npas4与Arnt的mRNA在树突中共定位，可能同时被翻译（Brigidi等，2019年）。