Polycalin (chlorophyllid A binding protein): a novel, very large fluorescent lipocalin from the midgut of the domestic silkworm Bombyx mori L.
We studied a protein from the midgut of the silkworm Bombyx mori characterized by its ability to bind the prosthetic group of chlorophyll, that confers fluorescent properties to this protein. Several techniques, 2D electrophoresis purification, MS-MS and Maldi-TOF peptide sequencing, RT-PCR and nucleotide sequencing were used to obtain the nucleotide sequence and the deduced amino acid sequence. The coding sequence was compared to the gene sequence to define the number and size of introns and exons. The gene spanned 45.5 kb of DNA and consisted of 46 exons. The cDNA encoded a protein of 2721 amino acids. The protein was identified as a lipocalin with novel features. Most lipocalins are proteins with high affinity to small lipophilic molecules, with a molecular size in the 25 kDa range and a well conserved tertiary structure. The apoprotein described here revealed 15 lipocalin like structures, in line. We called this protein a polycalin (pentadecacalin).
Mauchamp
Bernard
B
Unité Nationale Séricicole/INRA, 25 quai J.J. Rousseau, 69350 La Mulatière, France. mauchamp@clermont.inra.fr
Royer
Corinne
C
Garel
Annie
A
Jalabert
Audrey
A
Da Rocha
Martine
M
Grenier
Anne-Marie
AM
Labas
Valérie
V
Vinh
Joëlle
J
Mita
Kazuei
K
Kadono
Keiko
K
Chavancy
Gérard
G
D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000737:chemistry* / Q000235:genetics; D041981:Gastrointestinal Tract / Q000737:chemistry; D049750:Genome, Insect; D019476:Insect Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D019476:Insect Proteins