J. Biol. Chem., Vol. 265, Issue 32, 19447-19452, Nov, 1990
Arthropod hemocyanins. Molecular cloning and sequencing of cDNAs encoding the tarantula hemocyanin subunits a and e
R Voit and G Feldmaier-Fuchs
Zoologisches Institut, Universitat Munchen, Federal Republic of Germany.
cDNA clones comprising the entire coding region of two out of the seven
heterogeneous subunits of hemocyanin from the tarantula, Eurypelma
californicum, were isolated from four cDNA libraries constructed from total
RNA from the heart tissue of single spiders. Hybridization was first
carried out using a tarantula hemocyanin subunit e partial cDNA, and
several positive clones were isolated, including one containing a
2.2-kilobase full-length cDNA (lambda M1). The cDNA comprises an open
reading frame for 623 amino acids, 34 nucleotides of the 5'noncoding
region, and 286 nucleotides of the 3'-noncoding region. To select for other
hemocyanin subunits, two 17-mer oligonucleotide mixtures, corresponding to
the conserved regions in the copper A and copper B oxygen-binding site of
chelicerate hemocyanins, were used as probes. Among the positive clones
obtained, full-length cDNAs coding for subunit a were identified. The cDNA
sequence determined from clone lambda K1 provides an open reading frame
coding for 630 amino acids and includes the 5'- and 3'-noncoding regions.
Northern blot analysis revealed single transcripts for subunits a and e,
each 2.3 kilobases long. The cDNAs for subunits a and e were both found to
lack any leader peptide sequence. This supports the idea that the mature
protein accumulates in the cytoplasm and is released by cell rupture.