Krizaj David
Dept. of Ophthalmology, Beckman Vision Center, UCSF School of Medicine, Rm. K-140, 10 Kirkham St., San Francisco, CA 94143-0730, USA.
Exp Eye Res. 2005 Dec;81(6):690-9. doi: 10.1016/j.exer.2005.04.007. Epub 2005 Jun 20.
The sarcoplasmic-endoplasmic reticulum calcium ATPase (SERCA) is a key intracellular calcium transporter, which regulates cellular calcium concentration [Ca2+] by transporting Ca2+ ions from the cytosol into the endoplasmic reticulum. SERCA-mediated Ca2+ sequestration controls proper folding of newly synthesized proteins within the ER as well as the timing and spatial patterning of depolarization-evoked Ca2+ responses in the cytoplasm. To understand the spatial and temporal properties of Ca2+ homeostasis in retinal neurons better, I studied expression and distribution of all three SERCA isoforms in the mouse retina using isoform-specific antibodies. No immunostaining was observed with the SERCA1 antibody. SERCA2 was expressed in photoreceptor inner segments, amacrine and ganglion cells of the mouse retina. Similar SERCA2 localization was observed in adult rat, macaque and ground squirrel retinas. Analysis of distribution of SERCA2 immunofluorescence in the developing mouse retina revealed prominent SERCA2 signals throughout postnatal development. The N89 antibodys used to identify the SERCA3 isoforms labelled cone outer segments, inner segments of photoreceptors and cell processes in the inner nuclear layer of the mouse retina. These results imply that the SERCA2 isoform controls Ca2+ sequestration into the endoplasmic reticulum in most classes of retinal neuron. A potential role for SERCA3 in cone function is suggested.
肌浆网内质网钙ATP酶（SERCA）是一种关键的细胞内钙转运蛋白，它通过将钙离子从细胞质转运到内质网来调节细胞内钙浓度[Ca2+]。SERCA介导的钙螯合作用控制着内质网内新合成蛋白质的正确折叠，以及细胞质中去极化诱发的钙反应的时间和空间模式。为了更好地理解视网膜神经元中钙稳态的时空特性，我使用亚型特异性抗体研究了小鼠视网膜中所有三种SERCA亚型的表达和分布。使用SERCA1抗体未观察到免疫染色。SERCA2在小鼠视网膜的光感受器内节、无长突细胞和神经节细胞中表达。在成年大鼠、猕猴和地松鼠视网膜中也观察到了类似的SERCA2定位。对发育中小鼠视网膜中SERCA2免疫荧光分布的分析显示，在出生后的整个发育过程中都有明显的SERCA2信号。用于鉴定SERCA3亚型的N89抗体标记了小鼠视网膜的视锥细胞外节、光感受器内节和内核层中的细胞突起。这些结果表明，SERCA2亚型在大多数视网膜神经元类别中控制着钙向内质网的螯合作用。提示SERCA3在视锥细胞功能中可能发挥作用。
