Title : Human
lysosomal acid phosphatase is transported as a transmembrane
protein to lysosomes in transfected baby hamster kidney cells
Abstract :
- BHK cells transfected with human lysosomal acid phosphatase ( LAP ) cDNA (CT29 ) expressed 70-fold higher enzyme activities of acid phosphatase than non-transfected BHK cells
- The CT29- LAP was synthesized in BHK cells as a heterogeneously glycosylated precursor that was tightly membrane associated
- Transfer to the trans-Golgi was associated with a small increase in size (approximately 7 kd) and partial processing of the oligosaccharides to complex type structures
- CT29- LAP was transferred into lysosomes as shown by subcellular fractionation, immunofluorescence and immunoelectron microscopy
- Lack of mannose-6-phosphate residues suggested that transport does not involve mannose-6-phosphate receptors
- Part of the membrane-associated CT29- LAP was processed to a soluble form
- The mechanism that converts CT29- LAP into a soluble form was sensitive to NH4Cl, and reduced the size of the polypeptide by 7 kd
- In vitro translation of CT29-derived cRNA in the presence of microsomal membranes yielded a CT29- LAP precursor that is protected from proteinase K except for a small peptide of approximately 2 kd
- In combination with the sequence data available for LAP , these observations suggest that CT29- LAP is synthesized and transported to lysosomes as a transmembrane protein
- In the lysosomes, CT29- LAP is released from the membrane by proteolytic cleavage, which removes a C-terminal peptide including the transmembrane domain and the cytosolic tail of 18 amino acids
Output (sent_index, trigger,
protein,
sugar,
site):
- 2. glycosylated, , CT29, -, -
- 2. glycosylated, , precursor, -, -
Output(Part-Of) (sent_index,
protein,
site):
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):