描述：
Canine SCF (stem cell factor; also known as ckit ligand) is a type I transmembrane (TM)
glycoprotein that plays an important role in a number of fetal and adult developmental
processes. It is synthesized as a 274 amino acid (aa) precursor that contains a 25 aa signal
sequence, a 190 aa extracellular region, a 23 aa TM segment and a 36 aa cytoplasmic tail.
Within the extracellular region there are four potential Nlinked glycosylation sites, two
intrachain disulfide bonds, and four αhelices. Although the predicted molecular weight is
19 kDa, the native molecule is anywhere from 28 40 kDa in size and reflects both N-
and O-linked glycosylation . Glycosylation is not necessary for bioactivity. The transmembrane
form of SCF can be cleaved proteolytically, generating a 165 aa soluble form. Circulating
SCF exists as both a monomer and nondisulfidelinked homodimer, with monomer
predominating (50% to 75%). Both the soluble and TM forms have bioactivity. Their
principal targets may be different, however. A second, alternate splice short form of SCF has
been identified in other species. It is membrane bound but lacks the proteolytic cleavage site
found in the long form. Thus, it cannot give rise to a soluble molecule. No such isoform has
been reported for canine, but it could be assumed to exist. The ratio of long form to short
form varies from tissue to tissue. Soluble canine SCF shares 88%, 93%, 86%, 83%, 76%, 76%,
86% and 88% aa sequence identity with porcine, feline, bovine, human, mouse, rat, goat and
equine SCF, respectively. Cells known to express SCF include endothelial cells, fibroblasts and
keratinocytes.
原厂资料：
Canine SCF (stem cell factor; also known as ckit ligand) is a type I transmembrane (TM)
glycoprotein that plays an important role in a number of fetal and adult developmental
processes. It is synthesized as a 274 amino acid (aa) precursor that contains a 25 aa signal
sequence, a 190 aa extracellular region, a 23 aa TM segment and a 36 aa cytoplasmic tail.
Within the extracellular region there are four potential Nlinked glycosylation sites, two
intrachain disulfide bonds, and four αhelices. Although the predicted molecular weight is
19 kDa, the native molecule is anywhere from 28 40 kDa in size and reflects both N-
and O-linked glycosylation . Glycosylation is not necessary for bioactivity. The transmembrane
form of SCF can be cleaved proteolytically, generating a 165 aa soluble form. Circulating
SCF exists as both a monomer and nondisulfidelinked homodimer, with monomer
predominating (50% to 75%). Both the soluble and TM forms have bioactivity. Their
principal targets may be different, however. A second, alternate splice short form of SCF has
been identified in other species. It is membrane bound but lacks the proteolytic cleavage site
found in the long form. Thus, it cannot give rise to a soluble molecule. No such isoform has
been reported for canine, but it could be assumed to exist. The ratio of long form to short
form varies from tissue to tissue. Soluble canine SCF shares 88%, 93%, 86%, 83%, 76%, 76%,
86% and 88% aa sequence identity with porcine, feline, bovine, human, mouse, rat, goat and
equine SCF, respectively. Cells known to express SCF include endothelial cells, fibroblasts and
keratinocytes.
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