Chromosome-specific alpha satellites: Two distinct families on human chromosome 18

• Published in: Genomics (San Diego, Calif.) Vol. 11; no. 1; pp. 15 - 23
• Main Authors: Alexandrov, I.A., Mashkova, T.D., Akopian, T.A., Medvedev, L.I., Kisselev, L.L., Mitkevich, S.P., Yurov, Y.B.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.09.1991; Elsevier
• Subjects: Base Sequence; Biological and medical sciences; Chromosomes, Human, Pair 18; DNA, Satellite - genetics; Fundamental and applied biological sciences. Psychology; Genes. Genome; Humans; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Nucleic Acid Hybridization; Repetitive Sequences, Nucleic Acid; Sequence Homology, Nucleic Acid; Satellite DNA; Human; Molecular hybridization; Nucleotide sequence; E18-Chromosome; Repeated sequence; In situ; Molecular cloning
• ISSN: 0888-7543; 1089-8646
• DOI: 10.1016/0888-7543(91)90097-X

Two types of human chromosome 18-specific alpha satellite fragments have been cloned and sequenced. They represent closely related but distinct alphoid families formed by two different types of the higher-order repeated units (1360-bp EcoRI and 1700-bp HindIII fragments) that do not alternate in the genome. The individual repeats within each family are 99% identical and interfamily homology is about 78%. Sequence analysis shows that both repeats belong to alphoid suprachromosomal family 2, but their homology is not higher than that of family members located on different chromosomes. Therefore, the two repeats shared a common origin in the recent past, although they are not the direct offspring of one ancestral sequence. Our data indicate that these two 18-specific domains have appeared as a result of two separate amplification events. Despite the high degree of homology, they are not undergoing intrachromosomal homogenization, although some variation of this process might take place within each domain.