CTSL
CTSL (cathepsin L, also known as CTSL1 or FLJ31037) is a lysosomal cysteine proteinase of the peptidase C1 family. It plays a major role in intracellular protein catabolism and, through nuclear isoforms, in cell cycle regulation. Browse Assay Genie's current range of CTSL research reagents below, or read on for the biology behind the target.
CTSL is a lysosomal cysteine proteinase that plays a major role in intracellular protein catabolism. Its substrates include collagen and elastin, as well as alpha-1 protease inhibitor, a major controlling element of neutrophil elastase activity. A separate function relates to cell cycle progression: translation initiation at downstream start sites produces isoforms that lack a signal peptide and localise to the nucleus, where they cleave the CUX1 transcription factor and modify its DNA binding properties.
The CTSL gene encodes a precursor, procathepsin L, from which both chains of the mature enzyme are produced. The mature protein is a dimer of disulfide-linked heavy and light chains, both derived from this single precursor. It belongs to the peptidase C1 family and is classed by HGNC within the cathepsins, elastases and cysteine endopeptidases. UniProt records localisation to the lysosome, apical cell membrane, chromaffin granules, the extracellular space and the nucleus. Mouse and rat each have a Ctsl ortholog.
CTSL was previously named cathepsin L1, and CTSL1 remains a common alias. The protein has been implicated in several pathological processes, including myofibril necrosis in myopathies and myocardial ischaemia, and in the renal tubular response to proteinuria. CTSL also cleaves the S1 subunit of the SARS-CoV-2 spike protein, a step necessary for viral entry into the cell, which has made it a frequent subject of virology research alongside work on its roles in proteolysis and cell cycle control.
CTSL is a major contributor to intracellular protein catabolism in the lysosome, making it a core target for protein turnover studies.
Nuclear CTSL isoforms cleave the CUX1 transcription factor and alter its DNA binding properties, linking the protease to cell cycle progression.
CTSL cleaves the S1 subunit of the SARS-CoV-2 spike protein, a step necessary for entry of the virus into the cell.
CTSL has been implicated in myofibril necrosis, myocardial ischaemia and the renal tubular response to proteinuria.
CTSL is a lysosomal cysteine proteinase with a major role in intracellular protein catabolism. It cleaves substrates including collagen, elastin and alpha-1 protease inhibitor. Nuclear isoforms also process the CUX1 transcription factor, which regulates cell cycle progression. Check the datasheet of any product for its validated reactivity.
CTSL is also called cathepsin L1 (the previous HGNC name), with the symbols CTSL1 and FLJ31037 as aliases. UniProt lists the precursor as procathepsin L. The mature enzyme is a disulfide-linked dimer of heavy and light chains formed from a single precursor.
Mouse and rat both carry a Ctsl ortholog. In humans, CTSL has been implicated in myofibril necrosis in myopathies, myocardial ischaemia and the renal response to proteinuria. It also cleaves the SARS-CoV-2 spike S1 subunit, which is needed for viral cell entry.
Other cathepsins, lysosomal proteases and substrate-related targets with products at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P07711; product specifications from Assay Genie datasheets.