Identification of four small molecular mass proteins in the silk of Bombyx mori.
This paper describes cDNAs of four small-size proteins that occur in the cocoon silk of Bombyxmori. Two of them (9.9 and 10.3 kDa), which have the N-terminal sequences and the spacing of a few amino acids at C-termini similar to the seroin of Galleria mellonella, are called seroin 1 and seroin 2. The corresponding genes are expressed in the middle, and to a small extent also in the posterior silk gland sections. The seroin 1 and less conspicuously the seroin 2 mRNAs accumulate in the course of the last larval instar to a maximum in postspinning larvae. Two other proteins (6 kDa and 4.7 kDa) of B. mori cocoons were identified as a typical Kunitz-type and a somewhat unusual Kazal-type proteinase inhibitors, and named BmSPI 1 and BmSPI 2, respectively. Their genes are expressed in the middle, and the BmSPI 1 gene slightly also in the posterior silk gland sections. The expression ensues a few days after the last larval ecdysis and increases until the cocoon spinning. Post-spinning larvae still contain high amounts of the BmSPI 1 but no BmSPI 2 transcripts. It is assumed that seroins and proteinase inhibitors are involved in cocoon protection against predators and microbes.
Nirmala
X
X
Institute of Entomology, Academy of Sciences, and Faculty of Biological Sciences, University of South Bohemia, Ceské Budejovice, Czech Republic.
Mita
K
K
Vanisree
V
V
Zurovec
M
M
Sehnal
F
F
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D012831:Bombyx / Q000737:chemistry* / Q000235:genetics*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D030562:Databases, Protein; D020224:Expressed Sequence Tags; D006023:Glycoproteins / Q000737:chemistry; D019476:Insect Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics*; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D047011:Silk
D018076:DNA, Complementary; D006023:Glycoproteins; D019476:Insect Proteins; D011480:Protease Inhibitors; C112916:Seroin protein, Galleria mellonella; D047011:Silk