Modifications of the type and concentration of detergents and buffers used for thylakoid extraction and gel electrophoresis have provided improved resolution of chlorophyll-protein complexes in mutant barley which lacks chlorophyll b. The use of sodium deoxycholate in the gels and in the solubilization of thylakoids reduced the amount of free chlorophyll significantly. Three chlorophyll-a-protein complexes were resolved from mutant barley; two of these (CPla and CP1) represent the reaction centre complex of photosystem 1, while the third complex, CPa, is the presumed reaction centre of photosystem 2. The fluorescence emission band of mutant barley complex CPa at 684 nm and the low fluorescence yield are consistent with expected characteristics of a reaction centre complex of photosystem 2. More chlorophyll (60 %) is associated with the reaction centre complex of photosystem 1 than with the presumed reaction centre complex of photosystem 2 (30 %), and these amounts are double those found in the corresponding complexes of normal barley.
NK cells can co-express inhibitory and activating killer Ig-like receptors (KIR) recognizing the same HLA class I ligand. We present evidence from experiments with NK cells expressing both activating (KIR2DS2) and inhibitory (KIR2DL2 and KIR2DL3) receptors that the activating KIR can function without apparent interference from the inhibitory KIR. These studies used CD158b mAb that is equally reactive with KIR2DS2, KIR2DL2 and KIR2DL3. First, we show using plastic-immobilized CD158b mAb that the activating KIR2DS2 is stimulated, resulting in NK cell division and degranulation. Second, we show using soluble CD158b mAb and FcRII (+) P815 cells that high concentrations of CD158b mAb trigger the inhibitory KIR, whereas low concentrations stimulate the activating KIR2DS2 resulting in NK cell division and cytolysis. These results demonstrate that the activating KIR2DS2 can function on cells co-expressing the inhibitory KIR2DL2 and/or KIR2DL3, indicating the potential for independent function of activating KIR with natural ligand.
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