calcin是一组特异性激活兰尼碱受体（RyRs）的高亲和力蝎毒素穿膜多肽配体，活性0.3~375 nM，具有很好的应用于RyRs相关疾病的潜力。我们在前期研究8种天然calcin结构功能特性的基础上，从分子、细胞与整体动物三层面证实了代表性Imperacalcin具有主动释放并部分耗竭肌浆网Ca2+，抑制心肌细胞自发性Ca2+释放，拮抗以RyR2-R4496C突变小鼠为模型的CPVT室性期前收缩、非连续性双向室速等轻、中度症状的效应，但对连续性双向/多形性室速等严重症状的作用则相对有限。因此，本课题我们拟人工获取系列突变calcin，通过活性检测与生物信息学分析明确关键氨基酸、影响功能的重要氨基酸、非关键氨基酸以及模体片段信息等阐述其结构功能关系的同时对calcin进行人工优化，验证并提升其对CPVT的拮抗效应，期望筛选出活性更强、更具治疗CPVT等Ca2+紊乱性心律失常潜力的先导多肽。

Calcin is a set of globular cell-penetrating peptide ligands of ryanodine receptors (RyRs) with high affinity and exquisite selectivity. The defining characteristic of calcins is their capacity to stabilize RyR openings in a long-lasting subconducting state. They show a wide range of activities from 0.3 nM to 375 nM, therefore displaying a great potential to treat RyR-related diseases. Previously, we have provided a comprehensive analysis of the structure–function relationships of the nine known calcins, based on their primary sequence, three-dimensional modeling, and functional effects on skeletal RyRs. Using the RyR2-R4496C CPVT mouse model, we further confirmed the inhibition of Imperacalcin (the 1st calcin) on spontaneous Ca2+ releases by partial depletion of Ca2+ from sarcoplasmic reticulum in molecular and cellular levels. In intact mice, our investigations showed that Imperacalcin significantly antagonized the moderate symptoms of CPVT like premature ventricular contraction and discontinuous bidirectional ventricular tachycardia, but not the serious symptoms continuous bidirectional/polymorphic ventricular tachycardia. In this study, our first aim is to dissect the pivotal amino acids, functional important amino acids, non-pivotal amino acids, as well as the motif distribution that determine RyR pharmacology and thus to analyze the structure-function relationships, and the interaction of calcin-RyRs using a serious of manually synthesized calcin mutants. Then, we will design and optimize the calcins from primiary sequence and spatial structure, which will be further selected to optimize their capacity to antagonize the bidirectional/polymorphic tachyarrhythmias using the RyR2-R4496C mutant mice from the molecular, cellular and intact mice levels, therefore, to develop a novel paradigm for the treatment of calcium-dependent arrhythmias like CPVT, results may also be applied to other cardiomyopathies where controlled unloading of SR Ca2+ may be desirable.