Matrix Protein

Matrix Protein

Matrix Protein - Consists of two distinct peptides, la and lb, which are tightly but non-covalently associated with peptidoglycan. They are also associated with the lipoprotein.

A striking feature of these proteins is their very high content of β-structure, in contrast to many other intrinsic proteins which have high contents of α -helix.

There is evidence that the matrix proteins span the membrane. They form a hexagonal lattice structure covering about 60% or more of the peptidoglycan layer.

Three molecules of the protein probably form one hexagonal unit and enclose a channel which passes across the outer membrane.

Experimental evidence indicates that the matrix proteins form passive diffusion pores which permit rapid diffusion of small molecular weight hydrophilic molecules (MW <650) across the membrane.

Low molecular weight nutrients such as sugars, amino acids arid salts probably enter the periplasmic space from the outside through the matrix protein pores.

Nutrients having higher molecular weights require their own receptors to pass through the membrane.

The matrix proteins also serve as receptors for phages.

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