st-Ht31 (ammonium salt)

st-Ht31 is a cell-permeable stearated peptide derived from the amphipathic helix domain from A-kinase anchoring proteins (AKAPs), which binds protein kinase A (PKA).^1,2 It decreases PKA membrane anchoring but not activity in a reporter assay using BHK-21 fibroblasts when used at a concentration of 50 µM.² st-Ht31 (1 and 3 µM) reduces capacitance and peractivation, as well as prevents in vitro fertilization, in mouse sperm.¹ It increases cholesterol export from BHK-21 cells and RAW 264.7 macrophages expressing ATP-binding cassette transporter 1 (ABCA1) when used at a concentration of 50 µM.²