Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Q: Context: The authors describe a family with six patients with muscular dystrophy with a variable course. One is a compound heterozygote for CAPN3 mutations (calpainopathy) and the others have a single CAPN3 mutation. Linkage analysis and sequencing revealed a XK gene mutation (McLeod syndrome). This illustrates the variable phenotype of XK mutations and suggests the possibility that CAPN3 heterozygotes may have their condition caused by nonallelic mutations in other unrelated genes. 
 Question: Mutation of which gene is associated with McLeod syndrome?

A: xk
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Q: Context: Sidonie of Podebrady (Czech: Zdenka z Podebrad; 14 November 1449 -- 1 February 1510) was a daughter of George of Podebrady, King of Bohemia, and his first wife Kunigunde of Sternberg. 
 Question: Which lady gave birth to Sidonie of Podebrady?

A: kunigunde of sternberg
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Q: Context: Most selenoproteins contain a single selenocysteine residue per polypeptide chain, encoded by an in-frame UGA codon. Selenoprotein P is unique in that its mRNA encodes 10-12 selenocysteine residues, depending on species. In addition to the high number of selenocysteines, the protein is cysteine- and histidine-rich. The function of selenoprotein P has remained elusive, in part due to the inability to express the recombinant protein. This has been attributed to presumed inefficient translation through the selenocysteine/stop codons. Herein, we report for the first time the expression of recombinant rat selenoprotein P in a transiently transfected human epithelial kidney cell line, as well as the endogenously expressed protein from HepG2 and Chinese hamster ovary cells. The majority of the expressed protein migrates with the predicted 57-kDa size of full-length glycosylated selenoprotein P. Based on the histidine-rich nature of selenoprotein P, we have purified the recombinant and endogenously expressed proteins using nickel-agarose affinity chromatography. We show that the recombinant rat and endogenous human proteins react in Western blotting and immunoprecipitation assays with commercial anti-histidine antibodies. The ability to express, purify, and immunochemically detect the recombinant protein provides a foundation for investigating the functions and efficiency of expression of this intriguing protein. 
 Question: Which is the human selenoprotein that contains several Se-Cys residues?

A:
selenoprotein p
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