ABSTRACT
We determined the cDNA sequence and analyzed the genomic structure of a novel human gene designated HS24/p52, which shows significant similarity to the ATP-binding domain of stress-70 proteins in the human lung tumor cell line HS24. The 2,203-nucleotide-long cDNA sequence is divided into an incomplete 10-nucleotide 5' nontranslated region, a 1,425-nucleotide open reading frame which codes for 474 amino acids and a 768-nucleotide 3' nontranslated region. The first 404 of the deduced 474 amino acids resemble the amino-terminal regions of Hsp70 proteins from different species. Furthermore, single amino acid and short amino acid stretches, which are thought to be essential for the ATPase mechanism and ATP-binding activity in Hsp70 proteins, are conserved in this sequence, too. The carboxy-terminal 70 amino acids exhibit no significant similarity to hsp70 nor to any other known protein sequences. The HS24/p52 gene contains at least five introns, which differ significantly from hsc70 genes with regard to their size and location within the coding sequences. The total size of this gene is more than 15 kbp. Polymerase chain reaction (PCR) experiments showed that this gene is expressed in different human cell lines and tissues and it also seems to be highly conserved between human and mouse.
Subject(s)
DNA, Complementary/genetics , Genome, Human , HSP70 Heat-Shock Proteins/genetics , Lung Neoplasms/genetics , Amino Acid Sequence , Animals , Base Sequence , Humans , Mice , Molecular Sequence Data , Polymerase Chain Reaction , Sequence Alignment , Tumor Cells, CulturedABSTRACT
A calcium-binding protein was isolated from serum-free culture medium of human squamous carcinoma cells (HS 24). N-Terminal sequencing of the protein yielded 30 amino acids which were identical to the N-terminus of cystic fibrosis antigen. Northern blot analysis with an oligonucleotide derived from the N-terminus resulted in the detection of a transcript of approximately 600 bases. Screening of a HS 24-cDNA library with the same oligonucleotide led to the isolation of a 381-bp-cDNA encoding a protein of 93 amino acids. The corresponding protein has been identified as the calcium-binding protein MRP-8 usually found in Macrophages.
