Analysis of CAPS2 gene function

CAPS蛋白调节分泌部位（如神经末梢）含儿茶酚胺或神经肽的致密核心囊泡（DCV）的胞吐作用。然而，大量的CAPS蛋白定位于细胞索马中，并且体细胞CAPS蛋白的作用仍不清楚。我们发现，体CAPS 1在trans-Golgi网络中的致密核心囊泡（DCV）运输中起着重要作用。抗CAPS 1抗体似乎拉下膜组分，包括许多高尔基体相关蛋白，如ADP-核糖基化因子（ARF）小GTP酶。蛋白质-蛋白质相互作用的生化分析表明，CAPS 1特异性地与II类ARF 4/ARF 5相互作用，但不与其他类别的ARF，通过pleckstrin同源（PH）结构域在GDP结合的ARF形式特异性的方式。CAPS 1的PH结构域显示出对高尔基体膜的高亲和力，从而将ARF 4/ARF 5募集到高尔基体复合体。这些发现暗示CAPS 1蛋白在调节DCV在trans-Golgi网络中的运输中的功能作用。

CAPS protein regulates exocytosis of catecholamine- or neuropeptide-containing dense-core vesicles (DCVs) at secretion sites such as nerve terminals. However, large amounts of CAPS protein are localized in the cell soma, and the role of somal CAPS protein remains unclear. We showed that somal CAPS1 plays an important role in dense-core vesicle (DCV) trafficking in the trans-Golgi network. The anti-CAPS1 antibody appeared to pull down membrane fractions, including many Golgi-associated proteins such as ADP-ribosylation factor (ARF) small GTPases. Biochemical analyses of the protein-protein interaction showed that CAPS1 interacted specifically with the class II ARF4/ARF5, but not with other classes of ARFs, via the pleckstrin homology (PH) domain in a GDP-bound ARF form-specific manner. The PH domain of CAPS1 showed high affinity for the Golgi membrane, thereby recruiting ARF4/ARF5 to the Golgi complex. These findings implicate a functional role for CAPS1 protein in regulating DCV trafficking in the trans-Golgi network.