Related Experiment Video
Updated: Jul 31, 2026

Creating and Applying a Reference to Facilitate the Discussion and Classification of Proteins in a Diverse Group
Published on: August 16, 2017
Low molecular weight serine protease inhibitors from insects are proteins with highly conserved sequences
R A Boigegrain1, M Pugnière, P Paroutaud
1Laboratoire de Pathologie Comparée, INRA-CNRS, UMR 5087, Montpellier, France.
Abstract:
A low molecular weight protease inhibitor peptide found in ovaries of the desert locust Schistocerca gregaria (SGPI-2), was purified from plasma of the same locust and sequenced. It was named SGCI. It was found active towards chymotrypsin and human leukocyte elastase. SGCI was synthesized using a solid-phase procedure and the sequence of its reactive site for chymotrypsin was determined. Compared with an inhibitor purified earlier from another locust species, the total sequence of SGCI showed 88% identity. In particular, the sequence of the reactive site of these inhibitors was identical. Our search for a closely related peptide in an insect species far removed from locusts, the lepidopteran Spodoptera littoralis, was unfruitful but a different chymotrypsin inhibitor, belonging to the Kazal family, was found whose mass is greater than that of SGCI (20 vs 3.6 kDa). Its N-terminal sequence shares 80% identity with that of a chymotrypsin inhibitor purified earlier from the haemolymph of another lepidopteran. Conservation of the amino acid sequence in the reactive site seems to be an exception among protease inhibitors.
Related Concept Videos
Protein Families
Conservation of Protein Domains Over Different Proteins
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to form...
siRNA - Small Interfering RNAs
In the cytoplasm, siRNA is processed from a double-stranded RNA, which comes from either endogenous DNA transcription or exogenous sources like a virus. This double-stranded RNA is then cleaved by the ATP-dependent...
Multi-species Conserved Sequences
Although the genome of each species varies greatly from each other, a few sequences are highly conserved. Such conserved DNA...
Inhibitors of Viral Protein Synthesis

