Nota Su A Cer Lobelii Ten

Summary

Acer Lobelii Ten. has often been considered as a variety of Acer platanoides, the A. clears this doubtful position and points to the characters which differentiate A. Lobelii from other similar species.

A. Lobelii and A. cappadocicum (Acer laetum), belonging to the same series Picta, have a great affinity while great differences exist in the case of A. platanoides.

A. Lobelii has thicker leaves than A. platanoides which have whole lobes, the fruits are smaller and the calix is extremely hairy, petiole red on the lower side. The twigs are covered by a very whithe bloom. The bark of adult branches is bright green in colour and smooth, sometimes with white streaks while that of A. platanoides is grey or greyish-brown.

The bark of the trunks of A. Lobelii is also smooth with few orizontal fissures and ash-white in colour, A. platanoides has instead a bark with fine vertical fissures and which is grey in colour.

The two maples differ also for some biological characters: A. Lobelii freely produces root shoots while A. platanoides does not; in the former the flowers appear at the same time as the leaves while in the latter the leaves appear after the flowers.

The vegetation area of A. Lobelii is restricted to the Mediterranean basin and it can be considered exclusive of Italy where it grows in some places in Campania, Lucania and Calabria.

The whole of the morphological, dendrological and physiological characters point to the fact that A. Lobelii Ten. can not be considered as a variety of A. platanoides but as a definite species. Furthermore A. Lobelii, as A. cappadocicum, has to be considered as a relict of the tertiary era, while A. platanoides belongs to a following period.     

1H-NMR analysis of CD3-ϵ reveals the presence of turn-helix structures around the ITAM motif in an otherwise random coil cytoplasmic tail

The conformation adopted in solution by the cytoplasmic tail of CD3-ϵ has been analyzed by ¹H-nmr. The cytoplasmic tail is mostly random coil except for the amino acids conforming the immunoreceptor tyrosine-based activation motif (ITAM), YxxL/IxxxxxxxY xxL. Although the N-terminal Y xxL sequence of the motif is poorly folded, adopting 6-residue turn-like conformations with the Tyr side chain in two different orientations, the C-terminal Y xxL sequence is placed in a more complex structure involving a set of nonclassical α-helix turns and β-turns that comprises 11 amino acids. This structure is not modified by phosphorylation of the tyrosine residue. The differences in the conformation adopted around the two tyrosines of the ITAM motif suggest that they may play different roles pertaining to either binding signal transducing proteins or, alternatively, proteins involved in other processes such as endoplasmic reticulum location. © 1997 John Wiley & Sons, Inc. Biopoly 42: 75–88, 1997