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At KAICO, we produce various proteins using silkworms. This time, we’ll introduce an overview of ‘proteins’, which are considered central to life sciences.

What are Proteins, Exactly? 

Proteins are one of the primary components that make up our bodies. They are high-molecular-weight compounds where amino acids are linked in a chain, possessing infinite possibilities through combinations of 20 standard amino acids. Numerous proteins exist in hair, nails, muscles, and even in blood.

The protein structure is hierarchically formed, starting from the primary structure (amino acid sequence), progressing to secondary structure (α-helix and β-sheet), tertiary structure (overall folding), and sometimes quaternary structure (combination of multiple subunits).

This complex structure enables proteins’ diverse functions. For example, in enzymes, their catalytic function depends on the specific three-dimensional structure of the active site. The active site is formed when amino acid residues initially distant in the primary sequence become spatially proximate through folding.

Function Examples

• Enzymes: Possess substrate specificity and lower the activation energy of chemical reactions to facilitate them. Example: Ribonuclease breaks down RNA.
• Transport Proteins: Bind specific molecules and transport substances inside and outside cells. Example: Hemoglobin binds oxygen and transports it throughout the body.
• Signal Transduction: Transmit signals between and within cells. Example: Insulin receptors are involved in blood glucose regulation.
• Structural Proteins: Maintain cell and tissue morphology. Example: Keratin is the main component of hair and nails.
• Defensive Proteins: Protect the body from external threats. Example: Antibodies bind specific antigens and trigger immune responses.

Protein synthesis follows the central dogma:

• Transcription: DNA information is copied to mRNA.
• Translation: Amino acids are linked on ribosomes based on mRNA information.
• Post-translational Modification: Synthesized proteins may undergo chemical modifications. Examples include phosphorylation, glycosylation, and ubiquitination.

Recent Protein Research Topics

• Structural Biology Innovation: The emergence of cryo-electron microscopy (cryo-EM) has enabled structural analysis of proteins and complexes previously difficult to determine. This was even a Nobel Chemistry Prize theme in 2017.
• Structure Prediction: How proteins form correct three-dimensional structures was a long-standing mystery. However, approaches using artificial intelligence like Google DeepMind’s AlphaFold have dramatically improved protein structure prediction accuracy. The latest AlphaFold 3 was released in May 2024.
• Phase Separation Biology: The phenomenon of liquid-liquid phase separation (LLPS) provides a new perspective on protein behavior within cells. This is expected to contribute to understanding the formation mechanisms of membrane-less cellular organelles.

Proteins and Diseases

Protein abnormalities are associated with various diseases:

• Alzheimer’s Disease: Abnormal aggregation of amyloid-β protein
• Cystic Fibrosis: Mutation of CFTR membrane protein
• Sickle Cell Anemia: Structural abnormality of hemoglobin protein Understanding these disease mechanisms could lead to developing new treatment methods.

Proteins We Produce

Proteins can be produced using various expression systems like E. coli, yeast, insect cells, and animal cells.

Our silkworm-baculovirus system uses silkworms as bioreactors, potentially offering higher recombinant protein expression success rates compared to traditional microbial cells or cultured cells. This means we can potentially produce proteins that are difficult to generate in other expression systems.

KAICO utilizes Kyushu University’s original baculovirus genome and silkworm biotechnology as core technology, enabling us to produce target proteins within silkworm pupae.

Summary

Proteins play a central role in life activities. Understanding their structure and function is crucial across numerous fields including biology, medicine, and pharmaceuticals.

At KAICO, we leverage the ‘protein plant’ within silkworms to produce diverse proteins that can be applied to vaccines and reagents for pharmaceutical research and development. We are committed to research and development, aiming to deliver proteins produced in silkworms and the subsequent pharmaceuticals to the world.

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For more information about KAICO’s protein expression services, click here.