[Hannah LS (OP)]

Laveena asks:

In humans, are all naturally occurring proteins encoded in the DNA?

What do you think?

[Bored chemist]

Arguably, one of the most common proteins- collagen- is not coded for in DNA.

However the precursors are coded for.

[evan_au]

A lot of proteins and enzymes found in the human body are not coded in the human DNA.
...because our microbiome has DNA code for more proteins than does human DNA

To a lesser extent, some proteins are coded in viral RNA (ie not DNA)

[chris]

Two clever, and interesting answers so far! I'd not thought about collagen like that before...

[evan_au]

In the early days of studying the human genome, there were some estimates that suggested the human genome might contain as many as 100,000 protein-coding genes, in order to account for the observed number of proteins in the human body.

However, the Human Genome Project revealed "only" around 25,000 protein-coding genes.

The actual proteins in our body are based on segments of DNA, and these segments can be connected up in different ways to produce different proteins.

See: https://en.wikipedia.org/wiki/Alternative_splicing

[bigshell]

Prions are one fascinating example. They're proteins that can influence other proteins' shapes without DNA involvement.

[evan_au]

From another viewpoint:
- Amino Acids are the building blocks of proteins.
- As a chemical family, there are a large number of amino acids
- But living creatures on Earth only use 21 amino acids out of this large family

So you could imagine large numbers of proteins in hypothetical living creatures on other planets
- Containing amino acids which are not coded by human DNA...

[butlermichael]

Proteins are typically synthesized from instructions encoded in DNA, but there are some unique instances of proteins that aren't directly encoded in our DNA. Сoconut milk powder, for instance, contains proteins that are naturally occurring in coconuts, not specifically encoded in our genetic material. It's intriguing to explore how nature presents us with various protein structures beyond the traditional genetic coding.

[Bored chemist]

Proteins are typically synthesized from instructions encoded in DNA, but there are some unique instances of proteins that aren't directly encoded in our DNA. Сoconut milk powder, for instance, contains proteins that are naturally occurring in coconuts, not specifically encoded in our genetic material. It's intriguing to explore how nature presents us with various protein structures beyond the traditional genetic coding.

Coconut proteins are encoded in the coconut's DNA.