A nuclear gene encoding a light-induced transiently expressed protein that is localized in the chloroplast has been isolated from an EMBL3 library of pea DNA. The gene is a member of a multigene family. The sequence of the gene contains the complete reading frame of previously characterized cDNA clones and two introns in the 5' region of the protein coding sequence. Primer extension and S1 nuclease studies have defined the cap site. Two TATA boxes are found 5' to the initiating methionine codon. Only a limited homology is found between the presequence of the gene and transit sequences of other previously sequenced precursors. Isolated nuclei of pea have been labelled and the in vitro synthesized transcripts analysed. The results show that the light-dependent expression of the gene family is regulated at the level of transcription.

Representation of genomic kinetic sequence classes and sequence complexities were investigated in nuclear and polysomal RNA of the higher plant Petroselinum sativum (parsley). Two different methods indicated that most if not all polysomal poly(A) -RNA is transcribed from unique sequences. As measured by saturation hybridization in root callus and young leaves 8.7% and 6.2%, respectively, of unique DNA were transcribed in mRNA corresponding to 13.700 and 10.000 average sized genes. Unique nuclear DNA hybridized with an excess of polysomal poly(A)mRNA to the same extent as with total polysomal RNA. 3H-cDNA - poly(A)mRNA hybridization kinetics revealed the presence of two abundance classes with 9.200 and about 30 different mRNAs in leaves and two abundance classes with 10.500 and 960 different mRNAs in callus cells. The existence of plant poly(A)hnRNA was proven both by its fast kinetics of appearance, its length distribution larger than mRNA, and its sequence complexity a few times that of polysomal RNA.

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The distribution of the early light-inducible protein (ELIP) of pea (Pisum sativurn) between grana and stroma thylakoids was studied. An antibody raised against a bacterial-expressed fusion protein containing ELIP sequences was used.Illumination of dark-grown pea seedlings causes an accumulation of the ELIP in the thylakoid membranes with a maximum level at 16 h. During continuous illumination exceeding 16 h the level decreases again. The fractionation of thylakoid membranes of 48-h-illuminated pea seedlings in grana and stroma thylakoids reveals that there is no uniform distribution of ELIP in the thylakoids. Rather 60 -70% of ELIP was found in the stroma thylakoids and 30-40% in the grana thylakoids. This distribution is in accordance with that of photosystem 1 but not with that of photosystem 11. After Triton-X-100 solubilization almost all ELIP is found in the photosystem-I-containing fraction. This also supports an association of ELIP with photosystem I.

cDNA clones were isolated for a chloroplast protein, the mRNA of which is induced to maximum levels within 2-4 h after onset of illumination in five day old, etiolated pea seedlings.The cDNA library was constructed from poly(A)(+)-mRNA which was isolated from 4 h illuminated seedlings. The extremely short induction period of the early light induced protein(ELIP)-mRNA established the basis of our screening procedure. Colony hybridization experiments were performed with(32)P-labelled cDNA probes, synthesized from RNA of seedlings which had been exposed to different programs of illumination. Plasmid DNAs were isolated from colonies showing strong hybridization signals exclusively with cDNA corresponding to the 4 h-mRNA. Hybrid released translation of preselected plasmids p 17/C2 and p17/C4 revealed a peptide of Mr 24 000. After posttranslational importin vitro, the processed product of Mr 17 000 appears in the chloroplast. Using these clones, the expression of the ELIP-mRNA was investigated by DOT-hybridization. The ELIP-mRNA reaches maximum levels within 2-4 hours after onset of illumination. Our results correspond precisely to thein vivo characteristics and indicate positive identification of the sought clones.