
Renin, aka angiotensinogenase, is a 340 amino acid enzyme (which also acts as a hormone). Its molecular weight is 340 kDa.

It is secreted by the juxtaglomerular cells (JG) cells of the juxtaglomerular apparatus in response to 3 stimuli:
- Hypotension (baroreceptors)
- Decreased delivery of sodium or chloride to the distal tubule (macula densa)
- β1 adrenergic stimulation (sympathetic nervous system)

Renin uses its endopeptidase activity to cleave angiotensinogen, to yield angiotensin I. This is the first step in the activation of the renin-angiotensin-aldosterone system (RAAS)
References
https://en.wikipedia.org/wiki/Renin
https://link.springer.com/article/10.1007/BF00584260 - β1 adrenergic stimulation