Karlin S, Ghandour G
EMBO J. 1985 May;4(5):1217-23. doi: 10.1002/j.1460-2075.1985.tb03763.x.
Comparisons within and between the human, mouse and rabbit immunoglobulin-kappa gene (J-C region) DNA sequences are carried out in terms of three two-letter nucleotide alphabets: (i) S-W alphabet (W = A or T; S = G or C); (ii) P-Q alphabet which distinguishes purines (P = A or G) from pyrimidines (Q = C or T); and (iii) a 'control' E-F alphabet (E = A or C; F = G or T). All statistically significant direct repeats within each of the three sequences and all significant block identities (a set of consecutive matching letters) shared by two or more sequences are determined for each alphabet. By contrast to the S-W and E-F alphabets, the P-Q alphabet comparisons reveal an abundance of statistically significant block identities not seen at the nucleotide level. Various interpretations of these P-Q structures with respect to control and functional roles are considered.
对人类、小鼠和兔子免疫球蛋白κ基因（J-C区域）的DNA序列进行了内部和相互之间的比较，比较依据三个双字母核苷酸字母表展开：（i）S-W字母表（W = A或T；S = G或C）；（ii）P-Q字母表，该字母表区分嘌呤（P = A或G）和嘧啶（Q = C或T）；以及（iii）一个“对照”E-F字母表（E = A或C；F = G或T）。针对每个字母表，确定了三个序列中每个序列内所有具有统计学意义的直接重复序列，以及两个或更多序列共有的所有显著的连续匹配字母块（一组连续匹配字母）。与S-W和E-F字母表形成对比的是，P-Q字母表比较揭示了大量在核苷酸水平未见到的具有统计学意义的连续匹配字母块。考虑了关于这些P-Q结构在调控和功能作用方面的各种解释。
