Formation of the 67-kDa laminin receptor by acylation of the precursor

• Published in: Journal of cellular biochemistry Vol. 69; no. 3; pp. 244 - 251
• Main Authors: Butò, Simona, Tagliabue, Elda, Ardini, Elena, Magnifico, Alessandra, Ghirelli, Cristina, van den Brûle, Frédéric, Castronovo, Vincent, Colnaghi, Maria I., Sobel, Mark E., Ménard, Sylvie
• Format: Journal Article Web Resource
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.06.1998; Wiley Liss, Inc
• Subjects: Acylation; Antigens, Differentiation - chemistry; Biochemistry, biophysics & molecular biology; Biochimie, biophysique & biologie moléculaire; Cell Line; Chromatography, Affinity; Dimerization; Epitopes - chemistry; Fatty Acids - antagonists & inhibitors; Fatty Acids - biosynthesis; Fatty Acids/antagonists & inhibitors/biosynthesis; Galectin 3; Human health sciences; Humans; Hydroxylamine - chemistry; Laminin - metabolism; Life sciences; monomeric laminin receptor; Oncologie; Oncology; Protein Precursors - chemistry; Protein Precursors - metabolism; Protein Precursors/chemistry/metabolism; receptor maturation; Receptors, Laminin - biosynthesis; Receptors, Laminin - chemistry; Receptors, Laminin - metabolism; Receptors, Laminin/biosynthesis/chemistry/metabolism; Sciences de la santé humaine; Sciences du vivant; Solubility
• ISSN: 0730-2312; 1097-4644; 1097-4644
• DOI: 10.1002/(SICI)1097-4644(19980601)69:3<244::AID-JCB2>3.0.CO;2-R

Even though the involvement of the 67‐kDa laminin receptor (67LR) in tumor invasiveness has been clearly demonstrated, its molecular structure remains an open problem, since only a full‐length gene encoding a 37‐kDa precursor protein (37LRP) has been isolated so far. A pool of recently obtained monoclonal antibodies directed against the recombinant 37LRP molecule was used to investigate the processing that leads to the formation of the 67‐kDa molecule. In soluble extracts of A431 human carcinoma cells, these reagents recognize the precursor molecule as well as the mature 67LR and a 120‐kDa molecule. The recovery of these proteins was found to be strikingly dependent upon the cell solubilization conditions: the 67LR is soluble in NP‐40‐lysis buffer whereas the 37LRP is NP‐40‐insoluble. Inhibition of 67LR formation by cerulenin indicates that acylation is involved in the processing of the receptor. It is likely a palmitoylation process, as indicated by sensitivity of NP‐40‐soluble extracts to hydroxylamine treatment. Immunoblotting assays performed with a polyclonal serum directed against galectin3 showed that both the 67‐ and the 120‐kDa proteins carry galectin3 epitopes whereas the 37LRP does not. These data suggest that the 67LR is a heterodimer stabilized by strong intramolecular hydrophobic interactions, carried by fatty acids bound to the 37LRP and to a galectin3 cross‐reacting molecule. J. Cell. Biochem. 69:244–251, 1998. © 1998 Wiley‐Liss, Inc.