Connexin channels and phospholipids: association and modulation

Table 3 Tandem electrospray-mass spectroscopy identification of phospholipids associated with connexin channels – PE.

amu observed	amu expected	PE
(a) i – Cx26 unique, hemichannels
510.30	510.35	20:0 lyso
(b) i – Cx26 unique, plaques
480.32	480.30	18:1 lyso
502.32	502.29	20:4 lyso
706.64	706.57	34:0e
768.64	768.55	38:4
802.72	802.63	40:1
808.72	808.62	42:4p
846.64	846.60	44:7
(a) ii – Cx32 unique, hemichannels
766.60ϕ	766.53	38:5
(b) ii – Cx32 unique, plaques
766.60ϕ	766.53	38:5
(a) iii – common to Cx26 and Cx32, hemichannels
630.50	630.41	28:3
654.40	654.41	30:5
742.50ϕ	742.53	36:3
746.50ϕ	746.57	36:1
760.50	760.49	38:8
(b) iii – common to Cx26 and Cx32, plaques
742.50ϕ	742.53	36:3
746.50ϕ	746.57	36:1

PE phospholipids in (a) hemichannel-detergent micelles and in (b) junctional plaques containing (i) only Cx26, (ii) only Cx32, or (iii) that are in both Cx26 and Cx32 samples, after removal of phospholipids found in negative control samples that did not contain either connexin. Tables are collated by unique mass (amu), with tolerance ± 0.10 amu from expected. Species highlighted with ϕ are found in both isolated plaques and hemichannel preparations containing the same connexin isoform. PE = phosphatidylethanolamine. e = alkyl ether glycerol-alkyl chain linkage; p = plasmenyl glycerol-alkyl chain linkage; lyso = lysophospholipid. Absence of e or p denotation indicates conventional ester glycerol-alkyl chain linkage. n equals two to seven tandem electrospray-mass spectroscopy runs per sample.

ISSN: 1741-7007