Tags: Protein.
Signal peptidases are enzymes that convert secretory and some membrane proteins to their mature forms by cleaving their signal peptides from their N-terminals.Signal peptidases were initially observed in endoplasmic reticulum (ER)-derived membrane fractions isolated from mouse myeloma cells. The key observation by César Milstein and colleagues was that immunoglobulin light chains were produced in a higher molecular weight form which became processed by the ER membrane fraction.