Expression and processing of presenilins in control and sporadic Alzheimer’s disease (AD) brain. Western blot analysis of PS2. Membrane pellets were prepared from human prefrontal cortex as described in “Materials and Methods” and proteins (200 µg) separated by SDS-PAGE and transferred to membrane. Presenilin 2 (PS2) was detected using affinity-purified anti-PS2 antiserum (NT14). As a reference, 50 µg of total protein from (L/PS2) cells was loaded in lane 1. Lanes 3 through 6 consist of material from individuals with the diagnosis of sporadic AD; whereas, lanes 2 and 7 through 12 are from age-matched controls. (Bottom panel) Western blot analysis of PS1 from human brain. A similarly prepared membrane was probed with (NT1). Lane 1 was loaded with 50 µg of total protein from (L/PS1) cells. L/PS2, L cell expressing human PS2; L/PS1, L cell expressing human PS1; SAD, sporadic AD.