Molecular cloning and characterization of a novel tissue-specific calpain predominantly expressed in the digestive tract.
In the course of the genomic cloning of nCL-2, a stomach-specific calpain, we identified a genomic clone encoding a novel member of the calpain large subunit family and designated it 'nCL-4'. First, using exon sequences, we cloned the cDNA for mouse nCL-4. Based on this sequence, we also cloned the cDNAs for rat and human nCL-4. In the case of human nCL-4, the longest open reading frame encodes 690 amino acid residues (Mr 79095) with equal sequence similarities (50-55%) to both ubiquitous and organ-specific calpain large subunits from mammals. The deduced amino acid sequence revealed that nCL-4 is highly conserved among mammals. nCL-4 can be aligned without significant deletions or insertions, and, thus, like other calpains, can be divided into four domains (I-IV). The significant similarity of domains II and IV to those in conventional calpain large subunits suggests the potential protease activity and Ca2+-binding ability of nCL-4. Northern blot analysis revealed that the mRNA for nCL-4 is expressed predominantly in stomach and small intestine but not in uterus, suggesting specialized functions of nCL-4 in the digestive tract. When overexpressed in COS-7 cells, a specific band for nCL-4 was detected. In addition, the gene coding for nCL-4 was localized on human chromosome 1.
Lee
H J
HJ
Department of Molecular Biology, Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
Sorimachi
H
H
Jeong
S Y
SY
Ishiura
S
S
Suzuki
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002154:Calpain / Q000096:biosynthesis* / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005753:Gastric Mucosa / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D007421:Intestine, Small / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger; D051381:Rats; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D012333:RNA, Messenger; D002154:Calpain