摘要： PURPOSE. Hyperpolarization-activated cyclic nucleotide-gated 1 (HCN1) channels are widely expressed in the retina. In photoreceptors, the hyperpolarization-activated current (Ih) carried by HCN1 is important for shaping the light response. It has been shown in multiple systems that traf?cking HCN1 channels to speci?c compartments is key to their function. The localization of HCN1 in photoreceptors is concentrated in the plasma membrane of the inner segment (IS). The mechanisms controlling this localization are not understood. We previously identi?ed a di-arginine endoplasmic reticulum (ER) retention motif that negatively regulates the surface targeting of HCN1. In this study, we sought to identify a forward traf?cking signal that could counter the function of the ER retention signal. METHODS. We studied traf?cking of HCN1 and several mutants by imaging their subcellular localization in transgenic X. laevis photoreceptors. Velocity sedimentation was used to assay the assembly state of HCN1 channels. RESULTS. We found the HCN1 N-terminus can redirect a membrane reporter from outer segments (OS) to the plasma membrane of the IS. The sequence necessary for this behavior was mapped to a 20 amino acid region containing a leucine-based ER export motif. The ER export signal is necessary for forward traf?cking but not channel oligomerization. Moreover, this ER export signal alone counteracted the di-arginine ER retention signal. CONCLUSIONS. We identi?ed an ER export signal in HCN1 that functions with the ER retention signal to maintain equilibrium of HCN1 between the endomembrane system and the plasma membrane.