Sahu Giriraj, Sukumaran Sunitha, Bera Amal Kanti
1] Department of Biotechnology, Indian Institute of Technology Madras, Sardar Patel Road, Chennai - 600036, Tamil Nadu, India [2].
Department of Biotechnology, Indian Institute of Technology Madras, Sardar Patel Road, Chennai - 600036, Tamil Nadu, India.
Sci Rep. 2014 May 14;4:4955. doi: 10.1038/srep04955.
Stable expression of pannexin 1 (Panx1) and pannexin 3 (Panx3) resulted in functional gap junctions (GJs) in HeLa cells, but not in Neuro-2a (N2a) or PC-12 cells. The glycosylation pattern of expressed Panx1 varied greatly among different cell lines. In contrast to connexin (Cx) containing GJs (Cx-GJs), junctional conductance (Gj) of pannexin GJs (Panx-GJs) is very less sensitive to junctional voltage. Both Panx1 and Panx3 junctions favoured anionic dyes over cations to permeate. Though, carbenoxolone (CBX) and probenecid blocked Panx1 hemichannel activity, they had no effect on Panx1-GJs or Panx3-GJs. Extracellular loop 1 (E1) of Panx1 possibly bears the binding pocket. The Cx-GJ blocker heptanol blocked neither Panx1 hemichannel nor Panx-GJs. Unlike the GJs formed by most Cxs, CO2 did not uncouple Panx-GJs completely. Oxygen and glucose deprivation (OGD) caused lesser uncoupling of Panx-GJs compared to Cx43-GJs. These findings demonstrate properties of Panx-GJs that are distinctly different from Cx-GJs.
泛素连接蛋白1（Panx1）和泛素连接蛋白3（Panx3）的稳定表达在HeLa细胞中形成了功能性缝隙连接（GJs），但在Neuro-2a（N2a）或PC-12细胞中则未形成。在不同细胞系中，所表达的Panx1的糖基化模式差异很大。与含连接蛋白（Cx）的缝隙连接（Cx-GJs）相比，泛素连接蛋白缝隙连接（Panx-GJs）的连接电导（Gj）对连接电压的敏感性非常低。Panx1和Panx3连接都更有利于阴离子染料而非阳离子染料渗透。虽然，羧苯磺胺（CBX）和丙磺舒可阻断Panx1半通道活性，但它们对Panx1-GJs或Panx3-GJs没有影响。Panx1的细胞外环1（E1）可能具有结合口袋。Cx-GJ阻滞剂庚醇既不阻断Panx1半通道也不阻断Panx-GJs。与大多数Cx形成的缝隙连接不同，二氧化碳并未完全使Panx-GJs解偶联。与Cx43-GJs相比，氧和葡萄糖剥夺（OGD）导致Panx-GJs的解偶联程度较小。这些发现证明了Panx-GJs与Cx-GJs明显不同的特性。
