Jf. Lees et al., IDENTIFICATION OF THE MOLECULAR RECOGNITION SEQUENCE WHICH DETERMINESTHE TYPE-SPECIFIC ASSEMBLY OF PROCOLLAGEN, EMBO journal, 16(5), 1997, pp. 908-916
A key question relating to procollagen biosynthesis is the way in whic
h closely related procollagen chains discriminate between each other t
o assemble in a type-specific manner, Intracellular assembly of procol
lagen occurs via an initial interaction between the C-propeptides foll
owed by vectorial propagation of the triple-helical domain in the C to
N direction. Recognition signals within the C-propeptides must, there
fore, determine the selective association of individual procollagen ch
ains. We have used the pro alpha 1 chain of type III procollagen [pro
alpha 1(III)] and the pro alpha 2 chain of type I procollagen [pro alp
ha 2(I)] as examples of procollagen chains that are either capable or
incapable of self-assembly. When we exchanged the C-propeptides of the
pro alpha 1(III) chain and the pro alpha(I) chain we demonstrated tha
t this domain is both necessary and sufficient to direct the assembly
of homotrimers with correctly aligned triple-helices, To identify the
sequences within this domain that determine selective association we c
onstructed a series of chimeric procollagen chains in which we exchang
ed specific sequences from the pro alpha 1(III) C-propeptide with the
corresponding region within the pro alpha 2(I) C-propeptide (and vice
versa) and assayed for the ability of these molecules to form homotrim
ers. Using this approach we have identified a discontinuous sequence o
f 15 amino acids which directs procollagen self-association. By exchan
ging this sequence between different procollagen chains we can direct
chain association and, potentially, assemble molecules with defined ch
ain compositions.