Three heterotrimeric laminins produced by human keratinocytes

Laminins are a family of glycoproteins composed of α,β and γ chains. Five α(α1-α5), three β (β1–β3) and twoγ (γ1 and γ2) chains have been cloned fromhuman and their replaceable assembly into heterotrimers producesthe variety of laminins. Reverse transcription-polymerase chainreaction of mRNAs showed that human keratinocytes express theα3, α5, β1, β3, γ1 andγ2 genes at high level among the ten cloned lamininchains. Western blot and immunoprecipitation of the cell lysatewith antiserum directed against mouse laminin-1(α1β1γ1) detected two trimers with thecomposition of αxβ1γ1 (probablylaminin-10 with the composition of α5β1γ1and αyβ1γ1. Meanwhile, antiserum directedagainst a synthetic peptide of human α3 detected onlyα3β3γ2 trimer (laminin-5). We thus show thatkeratinocytes produce three heterotrimeric laminins. We couldnot detect the assembly of α3 with β1 and γ1chains to form α3β1γ1 (laminin-6) in keratinocytes.