We cloned a novel isoform of presenilin I (presenilin I-374) besides previously published presenilin I-467 and I-463 in human lymphocytes. Presenilin I-463 was identical to presenilin I-467 except a 12 bp nucleotides deletion in its amino terminal region. Another isoform, presenilin I-374 was produced by an alternative splicing with an additional exon consisting of 92 bp nucleotides (exon 11), which resulted in the frame shift with a stop codon to generate a truncated presenilin consisting of 374 amino acids. The transcripts for presenilin I-4671463 was ubiquitously detected while that for presenilin I-374 was selectively detected in liver, spleen, kidney. Abnormal behavior of presenilin I on gel electrophoresis was found with affinity-purified antibodies against presenilin I.
