β-lipotropin contains two lipolytic sequences ☆

Abstract The lipolytic activity of β-lipotropin (β-LPH) is commonly supposed to reside in the heptapeptide sequence, 47–53. However, β-endorphin is also lipolytically active, so a second active sequence must be postulated. In attempts to define this second sequence, porcine β-LPH, β-endorphin, 19 partial sequences of β-LPH, [Leu]enkephalin, and [D-Met 2 , Pro 5 ]-enkephalin amide have been examined for glycerol releasing activity in rabbit adipocytes. An N-terminal fragment of β-LPH lacking the 47–53 heptapeptide was inactive. The message within the C-terminal portion of β-LPH could be localized to a C-terminal sequence greater than 87–91, but probably smaller than 78–91.