Prohormones proenkephalin

Proenkephalin-A contains six copies of Met-enkephalin and one of the Leu-analog. Some of the probable cleavage products (e.g., Met-enkephalin-Arg-Gly-Leu) occur as normal constituents of adrenal chromaffin cells. /3-Endorphin originates from a prohormone which is the common precursor of ACTH, a-, and /3-melanocyte-stimulating hormone and /3-endorphin (the prohormone also includes the /3-lipotropin sequence)/227 ... 

Figure 2 Proneuropeptides structural features for proteolytic processing. Neuropeptides are synthesized as proneuropeptide precursors, also known as prohormones, that require proteolytic processing to liberate the active neuropeptide. Proteolytic processing occurs at dibasic and monobasic sites, as well as at multibasic sites. The precursor proteins may contain one copy of the active neuropeptide, such as the proneuropeptides for NPY, galanin, CRF, and vasopressin. Some proneuropeptides such as proenkephalin contain multiple copies of the active neuropeptide proenkephalin contains four copies of (Met)enkephalin (ME), one copy of (Leu)enkephalin (LE), and the related opioid peptides ME-Arg-Phe (H) and ME-Arg-Cly-Leu (O).

Activity-based prohling of active cysteine proteases identihed cathepsin L as a proenkephalin processing protease in secretory vesicles. The activity probe DCG-04, the biotinylated form of E64c that inhibits cysteine proteases, was used for specihc affinity labeling of the 27 kDa protease enzyme of the prohormone thiol protease (FTP) complex (18, 22), which represents... 

Schiller MR, Mende-Mueller L, Moran K, Meng M, Miller KW, Hook VY. Prohormone thiol protease (PTP) processing of recombinant proenkephalin. Biochemistry 1995 34 7988-7995. 

Yasothornsrikul S, Aaron W, Toneff T, Hook VY. Evidence for the proenkephalin processing enzyme prohormone thiol protease (PTP) as a multicatal)4ic cysteine protease complex activation by glutathione localized to secretory vesicles. Biochemistry 1999 8 7421-7430. 

Azaryan AV, Hook VYH. (1994) Unique cleavage specificity of prohormone thiol protease related to proenkephalin processing. FEBS Lett. 1994 341 197-202. 

All of the known endogenous opioids are derived from three different prohormones pro-opiomelanocortin (POMC), proenkephalin A, and proenkephalin B (prodynorphin) (Figure 31-2). The genes encoding these are expressed in the CNS and in other regions of the body (e.g., POMC is also produced in the adrenohypophysis and the gastrointestinal tract proenkephalin A is also produced in the adrenal medulla). What is important is that sites... 

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