Question

Beta barrels are present in mitochondria.The formation of a concentration gradient in the mitochondria is necessary for the efficient creation of ATP, such as hydrogen channels, but is this what these β-barrels are involved in, or do they have some other function?

Answer 1

Beta barrels:

These are the structures of large beta-sheet that twists and coils to form a closed structure in which the first strand is hydrogen bonded to the last. the strands in beta-barrels are typically arranged in an antiparallel fashion.

Types of beta barrels:

There are two types of beta barrels:

1. Up-and-down beta barrel

These are the simplest barrel topology and consist of a series of beta strands, each of which is hydrogen-bonded to the strands immediately before and after it in the primary sequence.

2. Jelly roll beta barrel

These beta barrels also known as the Swiss roll, is a complex nonlocal structure in which four pairs of antiparallel beta sheets, only one of which is adjacent in sequence, are "wrapped" in three dimensions to form a barrel shape.

Functions of beta barrels in mitochondria

A part from formation of a concentration gradient in the mitochondria for the creation of ATP beta barrela have following function in mitochondria.

• These transports protiens within the mitochondria. Within the mitochondrion two complexes exist with beta barrels serving as the pore forming subunit, Tom40 of the Translocase of the outer membrane, and Sam50 of the Sorting and assembly machinery.
• Sixteen to eighteen-stranded beta barrel structures are common in porins, which function as transporters for ions and small molecules that cannot diffuse across a cellular membrane.