EF hand

The EF hand is a helix-loop-helix structural domain or motif found in a large family of calcium-binding proteins.

The EF-hand motif contains a helix-loop-helix topology, much like the spread thumb and forefinger of the human hand, in which the Ca²⁺ ions are coordinated by ligands within the loop. The motif takes its name from traditional nomenclature used in describing the protein parvalbumin, which contains three such motifs and is probably involved in muscle relaxation via its calcium-binding activity.

The EF-hand consists of two alpha helices linked by a short loop region (usually about 12 amino acids) that usually binds calcium ions. EF-hands also appear in each structural domain of the signaling protein calmodulin and in the muscle protein troponin-C.

Calcium ion binding site

Hand

A hand (Latin manus) is a prehensile, multi-fingered organ located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "hand" and fingerprints remarkably similar to human fingerprints) are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking.

Fingers contain some of the densest areas of nerve endings on the body, are the richest source of tactile feedback, and have the greatest positioning capability of the body; thus the sense of touch is intimately associated with hands. Like other paired organs (eyes, feet, legs) each hand is dominantly controlled by the opposing brain hemisphere, so that handedness—the preferred hand choice for single-handed activities such as writing with a pencil, reflects individual brain functioning.

Some evolutionary anatomists use the term hand to refer to the appendage of digits on the forelimb more generally — for example, in the context of whether the three digits of the bird hand involved the same homologous loss of two digits as in the dinosaur hand.

Handwriting

Handwriting refers to a person's writing created with a writing utensil such as a pen or pencil. The term encompasses both printing and cursive styles and is separate from formal calligraphy or typeface. It is, in essence, a visible form of a person's voice, including pitch and tone.

The deterioration of a person's handwriting is also a symptom or result of certain diseases.

Uniqueness of handwriting

Each person has their own unique style of handwriting, whether it is everyday handwriting or their personal signature. Even identical twins who share appearance and genetics don't have the same handwriting. A person's handwriting is like that person's fingerprints: people might be able to copy it, but never write it in an identical way. The place where one grows up and the first language one learns melt together with the different distribution of force and ways of shaping words to create a unique style of handwriting for each person.

Characteristics of handwriting include:

Hand (surname)

Hand is a surname. Notable persons with that surname include: