Re: how much protein can a cell produce in one day

Thanks for your question, Dillon! This is a very complicated issue, but I can make some generalizations to get you in the approximate neighborhood, within a factor of a hundred or so. To take a guess, I'll need to get an estimate for the average size of a cell, which can be found here. Next, I'll need an estimate for the average half-life of a protein, which I'll take from here. Finally, I'll assume that the cell is neither growing nor shrinking, which allows me to simply say that the expression is equal to the amount needed to replace the protein lost. Growing cells could obviously make more.

So to remain a constant size, a cell containing about 50 picograms of protein which has a half-life of about 10 days would need to replace 25 picograms every 10 days, which would require synthesis of an average of 2.5 picograms per day.

So, knowing that an average cell(if there is such a thing) probably makes about 2.5 picograms/day, we can guesstimate that the upper limit for the biggest cell in the most permissive conditions would be around 250 pg/day, and possibly several times that if it was actively growing. Moderator note: Some cells in the body "professionally" produce proteins for secretion. These include mammary epithelial cells in the lactating breast, endocrine (hormone producing) cells of the pancreas, fibroblasts that secrete extracellular matrix, and Sertoli cells of the testis. I have been unable to find exact numbers, but I would expect these cells to be able to crank out an appreciable percentage of their mass each day.