Primary structure of the L subunit of the reaction center from Rhodopseudomonas sphaeroides.
The reaction center is an integral membrane protein that, together with several cofactors, mediates the primary photochemical events in bacterial photosynthesis. The amino-terminal sequences of the three subunits, L, M, and H, of the reaction center protein and the sequence of the structural gene encoding the M subunit have been reported previously. In the present study, we found that the 3' end of the structural gene encoding the L subunit overlaps by eight bases the 5' end of the gene encoding the M subunit. The primary structure of the L subunit has been determined from the nucleotide sequence of the gene and from analyses of the amino and carboxyl termini of the protein. The sequences of a number of tryptic and chymotryptic peptides were used to corroborate the nucleotide sequence. The L subunit was found to be composed of 281 amino acids (Mr 31,319) and to contain five hydrophobic segments. It is homologous to the M subunit and to a plant thylakoid protein referred to as the QB or Mr 32,000 protein.
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D002918:Chymotrypsin; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D005796:Genes; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D045322:Photosynthetic Reaction Center Complex Proteins; D012242:Rhodobacter sphaeroides / Q000378:metabolism*; D013045:Species Specificity; D014357:Trypsin
D001426:Bacterial Proteins; D046911:Macromolecular Substances; D010446:Peptide Fragments; D045322:Photosynthetic Reaction Center Complex Proteins; D004262:DNA Restriction Enzymes; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D002918:Chymotrypsin; D014357:Trypsin