https://www.biosyn.com/faq/What-does-%22canonical%22-mean-in-biology.aspx

Look at this discussion.

https://www.researchgate.net/post/What_is_the_difference_between_canonical_and_non-canonical_signalling_pathway

Thank you so much for your input~

In general, the term "canonical" refers to something that is standard, recognized, or widely accepted as the norm. In contrast, "non-canonical" refers to something that deviates from the standard or established norms.

In biology, the terms "canonical" and "non-canonical" are often used to describe molecular pathways, gene regulation, or protein interactions.

A "canonical pathway" refers to a well-characterized, frequently used, and essential signaling pathway that is widely conserved across different species. Canonical pathways are typically the most studied and well-understood pathways, and they are often the first to be identified and characterized.

On the other hand, a "non-canonical pathway" refers to a less well-understood, less frequently used, or specialized signaling pathway that may be unique to certain cell types, species, or conditions. Non-canonical pathways often have distinct regulatory mechanisms, signaling intermediates, or downstream targets compared to canonical pathways.

Similarly, in the context of gene regulation, "canonical" refers to the typical or most common mechanism of gene expression regulation, such as through the binding of transcription factors to the promoter region of a gene. "Non-canonical" gene regulation refers to alternative mechanisms that are less common or not well-understood, such as alternative splicing, RNA editing, or post-transcriptional modifications.

In summary, "canonical" and "non-canonical" are relative terms used to describe how closely a pathway or mechanism follows the established norm or standard. Canonical refers to the standard or established pathway, while non-canonical refers to pathways that deviate from this norm.