A novel chitin-binding protein identified from the peritrophic membrane of the cabbage looper, Trichoplusia ni.
A novel midgut peritrophic membrane (PM) protein, TnPM-P42, was identified from the cabbage looper, Trichoplusia ni. TnPM-P42 was shown as a 42kDa protein by SDS-PAGE analysis and appeared to be associated with the PM throughout its entire length. In T. ni larvae, the midgut is the only tissue where TnPM-P42 could be detected during the feeding period of the larvae. TnPM-P42 has chitin-binding activity and is strongly associated with the PM, which is similar to the currently known peritrophin type PM proteins. However, TnPM-P42 represents a unique family of proteins distinctly different from the peritrophin type PM proteins in its sequence characteristics. TnPM-P42 does not contain the peritrophin domain which is present in all the currently known PM proteins, but instead has a chitin deacetylase-like domain. Sequence similarity search of the GenBank database did not result in identification of any known proteins with a significant overall sequence similarity to the TnPM-P42. However, expressed sequence tags (ESTs) from various arthropods were identified to code for proteins with high sequence similarities to TnPM-P42, indicating the presence of TnPM-P42 homologs in other arthropods. Consistent with the identification of various ESTs from arthropods, Western blot analysis demonstrated the presence of a TnPM-P42-like protein in the PMs from Heliothis virescens and Helicoverpa zea larvae. The sequence characteristics of TnPM-P42 indicate that TnPM-P42 represents a novel family of insect proteins. However, its biochemical and physiological functions require further investigation.
Guo
Wei
W
Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA.
Li
Guoxun
G
Pang
Yi
Y
Wang
Ping
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002686:Chitin / Q000378:metabolism*; D018076:DNA, Complementary; D004591:Electrophoresis, Polyacrylamide Gel; D019476:Insect Proteins / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009036:Moths / Q000737:chemistry*; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D019476:Insect Proteins; D008565:Membrane Proteins; D002686:Chitin