I am not a biologist, and I have a probably dumb biological question. For some purpose, I need to understand the function of the CTNS gene, and here is the definition of it:
"This gene encodes a seven-transmembrane domain protein that functions to transport cystine out of lysosomes.
I did not know what cystine is, and when I checked Wikipedia, I see that "Cystine is the oxidized dimer form of the amino acid cysteine."
What I understand is lysosomes digest a bigger peptide, and cystine is created as a result, and it is taken out of lysosomes by the enzyme produced thanks to the gene CTNS. My question is, where does cystine go and what is it used for after leaving lysosomes? And is it ever broken further into monomers of cysteine?
I also read about a term "cysteine protease". What is its relation to cystine?