Recombine,It phages that encode the complete precursor polypeptide for the 22 kDa pol~cpeptide associated with photosystem it have been serologically selected fi'om two Agtll expression libraries made from polyadenylated RNA of spinach seedlings, The eDNAs hybridize to a 1.3 kb RNA species. The precursor protein is comprised of 274 amino acid residues and carries an N-terminal transit peptide of probably 69 amino acid residues, The mature protein exhibits Ibm' predicted transmembrane segments and is shown to be an integral component ofphotosystem It originating in a single-copy gene, The unique characteristics of this protein are: (i) it is the result of a eerie-internal duplication of an arJcestot with two ,rtembraqe spans, (it) a striking resemblance to LHC i/11, CP24/CP29 apoproteins, and ELIPs, although it does not bind chlorophyll and is p,'esent in cyanobacteria, mad. as these proteins, (iii) it integrates into the membrane with uncleared routing signals that display remarkable resemblance to patterns found in bipartite transit peptides, 22 kDa polypeptide

Five murine hybridoma lines that produce monoclonal antibodies against Epstein-Barr virus membrane antigen (MA) were established. Immunoprecipitation experiments demonstrated that three of the antibodies precipitated both the 236,000 (236K) MA and the 212K MA. The other two antibodies precipitated the 86K MA. Antibodies against the 236K-212K MA and the 86K MA mediated complement-dependent cytolysis of Epstein-Barr-virus-infected cells. The antibodies against the 86K MA neutralized both the B95-8 and P3HR-1 viruses.

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