Question: In molecular biology, the Cofactor transferase family is a family of protein domains that includes biotin protein ligases, etc, The metabolism of the cofactors lipoic acid and which water-soluble B-vitamin, also called vitamin B, and formerly known as vitamin H, or coenzyme R, share this family?
Context: In molecular biology, the vitamin B12-binding domain is a protein domain which binds to cobalamin (vitamin B12).  It can bind two different forms of the cobalamin cofactor, with cobalt bonded either to a methyl group (methylcobalamin) or to 5'-deoxyadenosine (adenosylcobalamin).  Cobalamin-binding domains are mainly found in two families of enzymes present in animals and prokaryotes, which perform distinct kinds of reactions at the cobalt-carbon bond.  Enzymes that require methylcobalamin carry out methyl transfer reactions.  Enzymes that require adenosylcobalamin catalyse reactions in which the first step is the cleavage of adenosylcobalamin to form cob(II)alamin and the 5'-deoxyadenosyl radical, and thus act as radical generators.  In both types of enzymes the B12-binding domain uses a histidine to bind the cobalt atom of cobalamin cofactors.  This histidine is embedded in a DXHXXG sequence, the most conserved primary sequence motif of the domain.  Proteins containing the cobalamin-binding domain include: Vitamin B, also called cobalamin, is a water-soluble vitamin that has a key role in the normal functioning of the brain and nervous system via the synthesis of myelin (myelinogenesis), and the formation of red blood cells.  It is one of eight B vitamins.  It is involved in the metabolism of every cell of the human body, especially affecting DNA synthesis, fatty acid and amino acid metabolism.  No fungi, plants, or animals (including humans) are capable of producing vitamin B. Only bacteria and archaea have the enzymes needed for its synthesis.  Some substantial sources of B include animal products (shellfish, meat), fortified food products, and dietary supplements. B is the largest and most structurally complicated vitamin and can be produced industrially through bacterial fermentation synthesis, typically used to manufacture B for fortified foods and supplements.  It can also be produced synthetically via vitamin B total synthesis. Streptavidin is a 52.8 kDa protein purified from the bacterium "Streptomyces avidinii".  Streptavidin homo-tetramers have an extraordinarily high affinity for biotin (also known as vitamin B7 or vitamin H).  With a dissociation constant (K) on the order of ≈10 mol/L, the binding of biotin to streptavidin is one of the strongest non-covalent interactions known in nature.  Streptavidin is used extensively in molecular biology and bionanotechnology due to the streptavidin-biotin complex's resistance to organic solvents, denaturants (e.g. guanidinium chloride), detergents (e.g. SDS, Triton), proteolytic enzymes, and extremes of temperature and pH. In biochemistry, biotinylation is the process of covalently attaching biotin to a protein, nucleic acid or other molecule.  Biotinylation is rapid, specific and is unlikely to perturb the natural function of the molecule due to the small size of biotin (MW = 244.31 g/mol).  Biotin binds to streptavidin and avidin with an extremely high affinity, fast on-rate, and high specificity, and these interactions are exploited in many areas of biotechnology to isolate biotinylated molecules of interest.  Biotin-binding to streptavidin and avidin is resistant to extremes of heat, pH and proteolysis, making capture of biotinylated molecules possible in a wide variety of environments.  Also, multiple biotin molecules can be conjugated to a protein of interest, which allows binding of multiple streptavidin, avidin or Neutravidin protein molecules and increases the sensitivity of detection of the protein of interest.  There is a large number of biotinylation reagents available that exploit the wide range of possible labelling methods.  Due to the strong affinity between biotin and streptavidin, the purification of biotinylated proteins has been a widely used approach to identify protein-protein interactions and post-translational events such as ubiquitylation in molecular biology. Biotin is a water-soluble B-vitamin, also called vitamin B and formerly known as vitamin H or coenzyme R. Biotin/lipoyl attachment domain has a conserved lysine residue that binds biotin or lipoic acid.  Biotin plays a catalytic role in some carboxyl transfer reactions and is covalently attached, via an amide bond, to a lysine residue in enzymes requiring this coenzyme.  Lipoamide acyltransferases have an essential cofactor, lipoic acid, which is covalently bound via an amide linkage to a lysine group.  The lipoic acid cofactor is found in a variety of proteins. In molecular biology, the Cofactor transferase family is a family of protein domains that includes biotin protein ligases, lipoate-protein ligases A, octanoyl-(acyl carrier protein):protein N-octanoyltransferases, and lipoyl-protein:protein N-lipoyltransferases.  The metabolism of the cofactors Biotin and lipoic acid share this family.  They also share the target modification domain ("Pfam PF00364" ), and the sulfur insertion enzyme ("Pfam PF04055" ). Avidin is a tetrameric biotin-binding protein produced in the oviducts of birds, reptiles and amphibians and deposited in the whites of their eggs.  There are also dimeric members of the avidin family found in some bacteria.  In chicken egg white, avidin makes up approximately 0.05% of total protein (approximately 180 μg per egg).  The tetrameric protein contains four identical subunits (homotetramer), each of which can bind to biotin (Vitamin B, vitamin H) with a high degree of affinity and specificity.  The dissociation constant of avidin is measured to be "K" ≈ 10 M, making it one of the strongest known non-covalent bonds. Pyridoxine 5’-phosphate oxidase is an enzyme that catalyzes several reactions in the vitamin B metabolism pathway.  Pyridoxine-5-P oxidase catalyzes the terminal step (also the rate-limiting step) in vitamin B metabolism, the biosynthesis of pyridoxal-5’-phosphate, the biologically active form of vitamin B which acts as an essential cofactor.  Pyridoxine 5’-phosphate oxidase is a member of the enzyme class oxidases, or more specifically, oxidoreductases.  These enzymes catalyze a simultaneous oxidation-reduction reaction.  The substrate oxidase enzymes is hydroxlyated by one oxygen atom of molecular oxygen. B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism.  Though these vitamins share similar names, research shows that they are chemically distinct vitamins that often coexist in the same foods.  In general, dietary supplements containing all eight are referred to as a vitamin B complex.  Individual B vitamin supplements are referred to by the specific number or name of each vitamin: B = thiamine, B = riboflavin, B = niacin, etc.  Some are better known by name than number: niacin, pantothenic acid, biotin and folate.
Answer: Biotin