To isolate proteins involved in hTERT transcriptional regulation, the HeLa cDNA library was screened using the hTERT promoter-based yeast one-hybrid assay. A positive clone was rescued and proved to contain an open reading frame and the upstream coding sequences were obtained by 5'-RACE. The assembled full cDNA consisted of a 2.5 kb reading frame encoding 834 amino acids, in which a conserved N-acetyltransferase domain (GNAT family) was searched out in bioinformatics, and thus named as hALP (human N-acetyltransferase-like protein, GenBank Accession No. AF 489535). The expression of native hALP was identified in HeLa cells and proved to distribute in the cellular nucleus. The binding potential of hALP to hTERT promoter was confirmed by EMSA and the interacting sequence involved to -201- to -56-nt upstream region of the promoter. On transfection assay, hALP could obviously transactivate hTERT promoter and stimulate endogenous telomerase activity of cells. The analysis on historic acetyltransferase showed that hALP could specifically acetylate free histones in vitro. The investigation suggested that hALP influences the activity of historic acetylation and could up-regulate telomerase activity through transactivation of hTERT promoter. (C) 2003 Elsevier Inc. All rights reserved.