Laminin isoforms

Figure 1. The muscle dystrophin-glycoprotein complex. The dystrophin-glycoprotein complex normally spans the plasma membrane of the skeletal muscle cell and may stabilize the sarcolemma and cytoskeleton to allow force transduction between the intracellular cytoskeleton (F-actin filaments) and the extracellular matrix. The molecules indicated are core components of the dystrophin-glycoprotein complex. Laminin 2 is the predominant laminin isoform in skeletal muscle basement membranes. Modified from McNeil and Steinhardt (2003)...

This short and selective review indicates that research into laminin structure and function has become increasingly sophisticated. The immediate future promises discovery of an increasing family of laminin isoforms, allowing the characterization of their biological activities, a more definitive map of the active domains and the peptides which subtend them, the working out of anti-laminin modulating influences, and characterisation of the receptors interacting with these domains in vivo to mediate cellular responses. Such study should clarify the contexts by which laminin exerts its powerful influence on neuronal development. 

Several of the amino acid sequences used for biomaterial modification correspond to motifs in laminin molecules. Studies have shown that some of the laminin isoforms provide much better support for pluripotent stem cells in vitro (Rodin et al., 2010). It is not known what isoforms that are preferred by growing neurites, but it is likely that there is some specificity also in this context. Consequently, specific motifs from preferred isoforms may be superior with respect to the regenerative support by a modified biomaterial. 

Laminin [consisting of three polypeptide chains, A, Bl (possibly replaced in GBM by S) and B2] is the most important noncollagenous protein of the glomerular basement membrane. Laminin forms a second network, which is connected to the collagen IV network probably via another protein called entactin or nidogen. Laminin is probably very important for cellular differentiation and adhesion, but its mesh clearly also contributes to the structure of the glomerular basement membrane. The postnatally common embryonic laminin-10 isoform is... 

KER, keratin, detected by a mixture of GAMS.2, MAK-6, and AEl /AE3 EMA, epithelial membrane antigen VIM, vimentin DES, desmin MSA, muscle-specific actin SMA, smooth muscle (alpha isoform) actin GALD, h-caldesmon S-IOOP, S-100 protein OCN, osteocalcin LM, laminin UL, Ulex europaeus I lectin binding FS, fibrosarcoma SGRMS, spindle cell rhabdomyosarcoma LMS, leiomyosarcoma MPNST, malignant peripheral nerve sheath tumor MSS, monophasic spindle cell synovial sarcoma SCAS, spindle cell angiosarcoma KS, Kaposi s sarcoma FOS, fibroblastic osteosarcoma. 

Cooper, H.M., Tamura, R.N. and Quaranta, V. (1991) The major laminin receptor of mouse embryonic stem cells is a novel isoform of the alpha-6 beta-1 integrin. J. Cell Biol. 115 843-850. 

Sanes, J.R., Engvall, E., Butkowski, R. and Hunter, D.D. (1990) Molecular heterogeneity of basal laminae isoforms of laminin and collagen IV at the neuromuscular junction and elsewhere. J. Cell Biol. Ill 1685-1699. 

At least 7 isoforms of laminin are known, each consisting of 3 different chains. Most extensively characterized of these is laminin-1 (M, 900,000) from mouse Engelbreth-Holm-Swarm tumor. [A.Utani etal. /. Biol. Chem. 270 (1995) 3292-3298 M.Nomizu etal.. Biol. Chem. 270 (1995) 20583-20590 CMatsui J. Biol. Chem. 270 (1995) 23496-23503 A.R.E.Shaw et al. / Biol. Chem 270 (1995) 24092-24099]... 

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