LOCALIZATION OF GUANYLATE CYCLASE ACTIVATING PROTEIN 2 IN MAMMALIAN RETINAS

当脊椎动物的眼睛暴露在光线下和 然后光线熄灭，神经中的光感受器杆状 视网膜必须重新建立一种暗适应状态。迈出的关键一步 这个过程是鸟苷酸酶在细胞内的刺激。 环化酶(GC)。GC激活蛋白(GCAP1和GCAP2)对GC的调节作用 激活。GC的GCap激活受浓度的调节 细胞内钙离子[Ca~(2+)]i。以前的研究 GCAP1定位于视杆外节、视锥外节、胞体和突触 终点站。在目前的研究中，我们使用了原位杂交和 GCAP2在人、猴和牛体内的免疫细胞化学定位 视网膜。在人类和猴子的视网膜中，最强烈的免疫标记 抗GCAP2抗体位于锥体内节段、胞体和胞体 突触终末，在较小程度上，在视杆内段 和视网膜内神经元。在牛视网膜中，最强烈的 免疫标记位于杆状内节段，标记较弱 锥形肌球、体细胞和突触。附加的酶分析使用 GCAP2特异性抗体证实GCAP1而不是GCAP2是 刺激牛杆外节GC的主要成分。 这些结果表明，尽管GCAP1参与了 视杆细胞和视锥细胞外节GCAP2对钙的敏感性调节 可能在光感受器和内部具有非光转导功能 视网膜神经元。尽管GCAP1和GCAP2突变在 人类视网膜疾病尚未确定，GC突变是 导致一种被称为Leber先天性视网膜病变的严重视网膜病变 黑猩猩。GCAP功能突变缺失的个体可能 预计会表现出类似的表型。

When the eyes of vertebrate animals have been exposed to light and then the light is extinguished, rod photoreceptors in the neural retina must re-establish a dark-adapted state. A critical step in this process is the intracellular stimulation of the enzyme guanylate cyclase (GC). GC-activating proteins (GCAP1 and GCAP2) modulate GC activation. GCAP activation of GC is regulated by the concentration of intracellular calcium ions [Ca2+]i. Previous studies have localized GCAP1 to rod and cone outer segments, somata and synaptic terminals. In the current study, we used in situ hybridization and immunocytochemistry to localize GCAP2 in human, monkey, and bovine retinas. In human and monkey retinas, the most intense immunolabeling with anti-GCAP2 antibodies was in the cone inner segments, somata and synaptic terminals and, to a lesser degree, in the rod inner segments and inner retinal neurons. In bovine retinas, the most intense immunolabeling was in the rod inner segments, with weaker labeling of cone myoids, somata and synapses. Additional enzymatic assays using a GCAP2-specific antibody confirmed that GCAP1, but not GCAP2, is the major component that stimulates GC in bovine rod outer segments. These results suggest that although GCAP1 is involved in the Ca2+-sensitive regulation of GC in rod and cone outer segments, GCAP2 may have non-phototransduction functions in photoreceptors and inner retinal neurons. Although the role of GCAP1 and GCAP2 mutations in human retinal diseases has yet to be established, mutations in GC are known to cause a severe retinopathy known as Leber's congenital amaurosis. Individuals with loss of function mutations in GCAPs might be expected to exhibit a similar phenotype.