Given the task definition and input, reply with output. Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Membrane-associated guanylate kinase (MAGUK) proteins are important determinants of ion channel organization in the plasma membrane. In the heart, the MAGUK protein SAP97, encoded by the DLG1 gene, interacts with several ion channels via their PDZ domain-binding motif and regulates their function and localization.', 'The purpose of this study was to assess in vivo the role of SAP97 in the heart by generating a genetically modified mouse model in which SAP97 is suppressed exclusively in cardiomyocytes.', 'SAP97(fl/fl) mice were generated by inserting loxP sequences flanking exons 1-3 of the SAP97 gene. SAP97(fl/fl) mice were crossed with MHC-Cre mice to generate MHC-Cre/SAP97(fl/fl) mice, thus resulting in a cardiomyocyte-specific deletion of SAP97. Quantitative reverse transcriptase-polymerase chain reaction, western blots, and immunostaining were performed to measure mRNA and protein expression levels, and ion channel localization. The patch-clamp technique was used to record ion currents and action potentials. Echocardiography and surface ECGs were performed on anesthetized mice.', 'Action potential duration was greatly prolonged in MHC-Cre/SAP97(fl/fl) cardiomyocytes compared to SAP97(fl/fl) controls, but maximal upstroke velocity was unchanged. This was consistent with the decreases observed in IK1, Ito, and IKur potassium currents and the absence of effect on the sodium current INa. Surface ECG revealed an increased corrected QT interval in MHC-Cre/SAP97(fl/fl) mice.
Does cardiac-specific ablation of synapse-associated protein SAP97 in mice decrease potassium currents but not sodium current?