psba2 a form of psba expressed only in cyanobacteria experiencing excitation stress or uvb stress e g campbell et al 1998 monitoring this protein can thus track when a cyanobacterial population is under excitation or uvb stress it is also specific to the sole constitutive form of psba in eukaryotic photobionts plants and algae 16 psab fpcdgpgrgg tc seq id no 16 this peptide sequence tag is specific to the psab core protein of photosystem i a key complex involved in transduction of light to chemical energy in all oxygenic photobionts 17 atpb368 cyvpaddltdp seq id no 17 atpb is one of the two major subunits of the f1 sub complex of atp synthases the atpb368 peptide sequence tag is conserved across the atpb subunits of chloroplasts photosynthetic and mitochondria respiratory in eukaryotes the target is also conserved in the atpb subunit of cyanobacterial atp synthase complexes which mediate both photosynthetic and respiratory generation of atp the target is also conserved in most bacterial f type atp synthase complexes but not in the v type atp synthase complexes found in archaea the antibody elicited using this peptide sequence tag thus can be used to detect the total community pool of chloroplastic mitochondrial and bacterial atp synthase the atp synthase complex is kinetically well characterized and so an estimation of the atp synthase complex allows further estimation of the community capacity for atp generation this key metabolic flux capacity can then be compared to flux capacities for other key processes such as carbon fixation or electron transport to identify rate limiting steps and acclimatory changes in community function 18 atpc32 ihsvarnpslakq seq id no 18 atpc is the main subunit of the f0 complex of atp synthases the atpc32 peptide sequence.