Gas channels, Sodium-coupled bicarbonate transporters.
Gas channels
Human Aquaporin 5, as well as many other aquaporins, besides their traditional function as water channels, can act as gas channels to transport CO2 and sometimes NH3.
Sodium-coupled bicarbonate transporters
The electroneutral sodium-bicarbonate transporter NBCn1 (SLC4A7) has many variants. We identified some novel variants and tested their function.
Structural determinants of hAQP5 as a CO2 channel
Human Aquaporin 5 is highly expressed in saliva gland and lung. We inject human aquaporin 5 RNA into Xenopus oocytes and used surface pH method to measure CO2 transport through oocytes. Using site-directed mutagenesis, we could identify the structural determinants of CO2 transport for hAQP5.
pHi recovery activity of NBCn1
Though different NBCn1 variants share some structural similarity, the pHi recovery activity is quite different. We tested pHi recovery activity of some mouse NBCn1 variants and used biotinylation method to see their surface expression. We found some cassette is stimulatory to the activity of NBCn1.
